--- a/tools/profiler/core/ProfileBuffer.cpp
+++ b/tools/profiler/core/ProfileBuffer.cpp
@@ -3,16 +3,18 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "ProfileBuffer.h"
 
 #include "ProfilerMarker.h"
 
+using namespace mozilla;
+
 ProfileBuffer::ProfileBuffer(int aEntrySize)
   : mEntries(mozilla::MakeUnique<ProfileBufferEntry[]>(aEntrySize))
   , mWritePos(0)
   , mReadPos(0)
   , mEntrySize(aEntrySize)
   , mGeneration(0)
 {
 }
@@ -51,41 +53,68 @@ ProfileBuffer::AddThreadIdEntry(int aThr
     // This is the start of a sample, so make a note of its location in |aLS|.
     aLS->mGeneration = mGeneration;
     aLS->mPos = mWritePos;
   }
   AddEntry(ProfileBufferEntry::ThreadId(aThreadId));
 }
 
 void
-ProfileBuffer::AddDynamicStringEntry(const char* aStr)
-{
-  size_t strLen = strlen(aStr) + 1;   // +1 for the null terminator
-  for (size_t j = 0; j < strLen; ) {
-    // Store up to kNumChars characters in the entry.
-    char chars[ProfileBufferEntry::kNumChars];
-    size_t len = ProfileBufferEntry::kNumChars;
-    if (j + len >= strLen) {
-      len = strLen - j;
-    }
-    memcpy(chars, &aStr[j], len);
-    j += ProfileBufferEntry::kNumChars;
-
-    AddEntry(ProfileBufferEntry::DynamicStringFragment(chars));
-  }
-}
-
-void
 ProfileBuffer::AddStoredMarker(ProfilerMarker *aStoredMarker)
 {
   aStoredMarker->SetGeneration(mGeneration);
   mStoredMarkers.insert(aStoredMarker);
 }
 
 void
+ProfileBuffer::CollectNativeLeafAddr(void* aAddr)
+{
+  AddEntry(ProfileBufferEntry::NativeLeafAddr(aAddr));
+}
+
+void
+ProfileBuffer::CollectJitReturnAddr(void* aAddr)
+{
+  AddEntry(ProfileBufferEntry::JitReturnAddr(aAddr));
+}
+
+void
+ProfileBuffer::CollectCodeLocation(
+  const char* aLabel, const char* aStr, int aLineNumber,
+  const Maybe<js::ProfileEntry::Category>& aCategory)
+{
+  AddEntry(ProfileBufferEntry::Label(aLabel));
+
+  if (aStr) {
+    // Store the string using one or more DynamicStringFragment entries.
+    size_t strLen = strlen(aStr) + 1;   // +1 for the null terminator
+    for (size_t j = 0; j < strLen; ) {
+      // Store up to kNumChars characters in the entry.
+      char chars[ProfileBufferEntry::kNumChars];
+      size_t len = ProfileBufferEntry::kNumChars;
+      if (j + len >= strLen) {
+        len = strLen - j;
+      }
+      memcpy(chars, &aStr[j], len);
+      j += ProfileBufferEntry::kNumChars;
+
+      AddEntry(ProfileBufferEntry::DynamicStringFragment(chars));
+    }
+  }
+
+  if (aLineNumber != -1) {
+    AddEntry(ProfileBufferEntry::LineNumber(aLineNumber));
+  }
+
+  if (aCategory.isSome()) {
+    AddEntry(ProfileBufferEntry::Category(int(*aCategory)));
+  }
+}
+
+void
 ProfileBuffer::DeleteExpiredStoredMarkers()
 {
   // Delete markers of samples that have been overwritten due to circular
   // buffer wraparound.
   uint32_t generation = mGeneration;
   while (mStoredMarkers.peek() &&
          mStoredMarkers.peek()->HasExpired(generation)) {
     delete mStoredMarkers.popHead();

--- a/tools/profiler/core/ProfileBuffer.h
+++ b/tools/profiler/core/ProfileBuffer.h
@@ -8,17 +8,17 @@
 
 #include "platform.h"
 #include "ProfileBufferEntry.h"
 #include "ProfilerMarker.h"
 #include "ProfileJSONWriter.h"
 #include "mozilla/RefPtr.h"
 #include "mozilla/RefCounted.h"
 
-class ProfileBuffer final
+class ProfileBuffer final : public ProfilerStackCollector
 {
 public:
   explicit ProfileBuffer(int aEntrySize);
 
   ~ProfileBuffer();
 
   // LastSample is used to record the buffer location of the most recent
   // sample for each thread. It is used for periodic samples stored in the
@@ -37,19 +37,26 @@ public:
 
   // Add |aEntry| to the buffer, ignoring what kind of entry it is.
   void AddEntry(const ProfileBufferEntry& aEntry);
 
   // Add to the buffer a sample start (ThreadId) entry for aThreadId. Also,
   // record the resulting generation and index in |aLS| if it's non-null.
   void AddThreadIdEntry(int aThreadId, LastSample* aLS = nullptr);
 
-  // Add to the buffer a dynamic string. It'll be spread across one or more
-  // DynamicStringFragment entries.
-  void AddDynamicStringEntry(const char* aStr);
+  virtual mozilla::Maybe<uint32_t> Generation() override
+  {
+    return mozilla::Some(mGeneration);
+  }
+
+  virtual void CollectNativeLeafAddr(void* aAddr) override;
+  virtual void CollectJitReturnAddr(void* aAddr) override;
+  virtual void CollectCodeLocation(
+    const char* aLabel, const char* aStr, int aLineNumber,
+    const mozilla::Maybe<js::ProfileEntry::Category>& aCategory) override;
 
   // Maximum size of a frameKey string that we'll handle.
   static const size_t kMaxFrameKeyLength = 512;
 
   void StreamSamplesToJSON(SpliceableJSONWriter& aWriter, int aThreadId,
                            double aSinceTime, JSContext* cx,
                            UniqueStacks& aUniqueStacks) const;
   void StreamMarkersToJSON(SpliceableJSONWriter& aWriter, int aThreadId,

--- a/tools/profiler/core/platform.cpp
+++ b/tools/profiler/core/platform.cpp
@@ -17,17 +17,17 @@
 //   call (profiler_get_backtrace()). It involves writing a stack trace and
 //   little else into a temporary ProfileBuffer, and wrapping that up in a
 //   ProfilerBacktrace that can be subsequently used in a marker. The sampling
 //   is done on-thread, and so Registers::SyncPopulate() is used to get the
 //   register values.
 //
 // - A "backtrace" sample is the simplest kind. It is done in response to an
 //   API call (profiler_suspend_and_sample_thread()). It involves getting a
-//   stack trace and passing it to a callback function; it does not write to a
+//   stack trace via a ProfilerStackCollector; it does not write to a
 //   ProfileBuffer. The sampling is done from off-thread, and so uses
 //   SuspendAndSampleAndResumeThread() to get the register values.
 
 #include <algorithm>
 #include <ostream>
 #include <fstream>
 #include <sstream>
 #include <errno.h>
@@ -49,17 +49,19 @@
 #include "mozilla/StaticPtr.h"
 #include "ThreadInfo.h"
 #include "nsIHttpProtocolHandler.h"
 #include "nsIObserverService.h"
 #include "nsIXULAppInfo.h"
 #include "nsIXULRuntime.h"
 #include "nsDirectoryServiceUtils.h"
 #include "nsDirectoryServiceDefs.h"
+#include "nsJSPrincipals.h"
 #include "nsMemoryReporterManager.h"
+#include "nsScriptSecurityManager.h"
 #include "nsXULAppAPI.h"
 #include "nsProfilerStartParams.h"
 #include "ProfilerParent.h"
 #include "mozilla/Services.h"
 #include "nsThreadUtils.h"
 #include "ProfilerMarkerPayload.h"
 #include "shared-libraries.h"
 #include "prdtoa.h"
@@ -652,69 +654,81 @@ public:
   Address mLR;    // ARM link register.
 #if defined(GP_OS_linux) || defined(GP_OS_android)
   // This contains all the registers, which means it duplicates the four fields
   // above. This is ok.
   ucontext_t* mContext; // The context from the signal handler.
 #endif
 };
 
-static void
-AddPseudoEntry(PSLockRef aLock, NotNull<RacyThreadInfo*> aRacyInfo,
-               const js::ProfileEntry& entry, ProfileBuffer& aBuffer)
+static bool
+IsChromeJSScript(JSScript* aScript)
 {
   // WARNING: this function runs within the profiler's "critical section".
 
+  nsIScriptSecurityManager* const secman =
+    nsScriptSecurityManager::GetScriptSecurityManager();
+  NS_ENSURE_TRUE(secman, false);
+
+  JSPrincipals* const principals = JS_GetScriptPrincipals(aScript);
+  return secman->IsSystemPrincipal(nsJSPrincipals::get(principals));
+}
+
+static void
+AddPseudoEntry(uint32_t aFeatures, NotNull<RacyThreadInfo*> aRacyInfo,
+               const js::ProfileEntry& entry,
+               ProfilerStackCollector& aCollector)
+{
+  // WARNING: this function runs within the profiler's "critical section".
+  // WARNING: this function might be called while the profiler is inactive, and
+  //          cannot rely on ActivePS.
+
   MOZ_ASSERT(entry.kind() == js::ProfileEntry::Kind::CPP_NORMAL ||
              entry.kind() == js::ProfileEntry::Kind::JS_NORMAL);
 
-  aBuffer.AddEntry(ProfileBufferEntry::Label(entry.label()));
-
   const char* dynamicString = entry.dynamicString();
   int lineno = -1;
 
   // XXX: it's unclear why the computation of lineno should depend on
   // |dynamicString|. Perhaps it shouldn't?
 
   if (dynamicString) {
-    // Adjust the dynamic string as necessary.
-    if (ActivePS::FeaturePrivacy(aLock)) {
-      dynamicString = "(private)";
-    } else if (strlen(dynamicString) >= ProfileBuffer::kMaxFrameKeyLength) {
-      dynamicString = "(too long)";
-    }
-
-    // Store the string using one or more DynamicStringFragment entries.
-    aBuffer.AddDynamicStringEntry(dynamicString);
+    bool isChromeJSEntry = false;
     if (entry.isJs()) {
       JSScript* script = entry.script();
       if (script) {
+        isChromeJSEntry = IsChromeJSScript(script);
         if (!entry.pc()) {
           // The JIT only allows the top-most entry to have a nullptr pc.
           MOZ_ASSERT(&entry == &aRacyInfo->entries[aRacyInfo->stackSize() - 1]);
         } else {
           lineno = JS_PCToLineNumber(script, entry.pc());
         }
       }
     } else {
       lineno = entry.line();
     }
+
+    // Adjust the dynamic string as necessary.
+    if (ProfilerFeature::HasPrivacy(aFeatures) && !isChromeJSEntry) {
+      dynamicString = "(private)";
+    } else if (strlen(dynamicString) >= ProfileBuffer::kMaxFrameKeyLength) {
+      dynamicString = "(too long)";
+    }
+
   } else {
     // XXX: Bug 1010578. Don't assume a CPP entry and try to get the line for
     // js entries as well.
     if (entry.isCpp()) {
       lineno = entry.line();
     }
   }
 
-  if (lineno != -1) {
-    aBuffer.AddEntry(ProfileBufferEntry::LineNumber(lineno));
-  }
-
-  aBuffer.AddEntry(ProfileBufferEntry::Category(int(entry.category())));
+  aCollector.CollectCodeLocation(entry.label(), dynamicString, lineno,
+                                 Some(entry.category()));
 }
 
 // Setting MAX_NATIVE_FRAMES too high risks the unwinder wasting a lot of time
 // looping on corrupted stacks.
 //
 // The PseudoStack frame size is found in PseudoStack::MaxEntries.
 static const size_t MAX_NATIVE_FRAMES = 1024;
 static const size_t MAX_JS_FRAMES     = 1024;
@@ -742,40 +756,45 @@ struct AutoWalkJSStack
 
   ~AutoWalkJSStack() {
     if (walkAllowed) {
       WALKING_JS_STACK = false;
     }
   }
 };
 
+// Merges the pseudo-stack, native stack, and JS stack, outputting the details
+// to aCollector.
 static void
-MergeStacksIntoProfile(PSLockRef aLock, bool aIsSynchronous,
-                       const ThreadInfo& aThreadInfo, const Registers& aRegs,
-                       const NativeStack& aNativeStack, ProfileBuffer& aBuffer)
+MergeStacks(uint32_t aFeatures, bool aIsSynchronous,
+            const ThreadInfo& aThreadInfo, const Registers& aRegs,
+            const NativeStack& aNativeStack,
+            ProfilerStackCollector& aCollector)
 {
   // WARNING: this function runs within the profiler's "critical section".
+  // WARNING: this function might be called while the profiler is inactive, and
+  //          cannot rely on ActivePS.
 
   NotNull<RacyThreadInfo*> racyInfo = aThreadInfo.RacyInfo();
   js::ProfileEntry* pseudoEntries = racyInfo->entries;
   uint32_t pseudoCount = racyInfo->stackSize();
   JSContext* context = aThreadInfo.mContext;
 
   // Make a copy of the JS stack into a JSFrame array. This is necessary since,
   // like the native stack, the JS stack is iterated youngest-to-oldest and we
   // need to iterate oldest-to-youngest when adding entries to aInfo.
 
   // Synchronous sampling reports an invalid buffer generation to
   // ProfilingFrameIterator to avoid incorrectly resetting the generation of
   // sampled JIT entries inside the JS engine. See note below concerning 'J'
   // entries.
-  uint32_t startBufferGen;
-  startBufferGen = aIsSynchronous
-                 ? UINT32_MAX
-                 : aBuffer.mGeneration;
+  uint32_t startBufferGen = UINT32_MAX;
+  if (!aIsSynchronous && aCollector.Generation().isSome()) {
+    startBufferGen = *aCollector.Generation();
+  }
   uint32_t jsCount = 0;
   JS::ProfilingFrameIterator::Frame jsFrames[MAX_JS_FRAMES];
 
   // Only walk jit stack if profiling frame iterator is turned on.
   if (context && JS::IsProfilingEnabledForContext(context)) {
     AutoWalkJSStack autoWalkJSStack;
     const uint32_t maxFrames = ArrayLength(jsFrames);
 
@@ -877,17 +896,17 @@ MergeStacksIntoProfile(PSLockRef aLock, 
     // Check to see if pseudoStack frame is top-most.
     if (pseudoStackAddr > jsStackAddr && pseudoStackAddr > nativeStackAddr) {
       MOZ_ASSERT(pseudoIndex < pseudoCount);
       js::ProfileEntry& pseudoEntry = pseudoEntries[pseudoIndex];
 
       // Pseudo-frames with the CPP_MARKER_FOR_JS kind are just annotations and
       // should not be recorded in the profile.
       if (pseudoEntry.kind() != js::ProfileEntry::Kind::CPP_MARKER_FOR_JS) {
-        AddPseudoEntry(aLock, racyInfo, pseudoEntry, aBuffer);
+        AddPseudoEntry(aFeatures, racyInfo, pseudoEntry, aCollector);
       }
       pseudoIndex++;
       continue;
     }
 
     // Check to see if JS jit stack frame is top-most
     if (jsStackAddr > nativeStackAddr) {
       MOZ_ASSERT(jsIndex >= 0);
@@ -903,49 +922,48 @@ MergeStacksIntoProfile(PSLockRef aLock, 
       // amount of time, such as in nsRefreshDriver. Problematically, the
       // stored backtrace may be alive across a GC during which the profiler
       // itself is disabled. In that case, the JS engine is free to discard its
       // JIT code. This means that if we inserted such OptInfoAddr entries into
       // the buffer, nsRefreshDriver would now be holding on to a backtrace
       // with stale JIT code return addresses.
       if (aIsSynchronous ||
           jsFrame.kind == JS::ProfilingFrameIterator::Frame_Wasm) {
-        aBuffer.AddEntry(ProfileBufferEntry::Label(""));
-        aBuffer.AddDynamicStringEntry(jsFrame.label);
+        aCollector.CollectCodeLocation("", jsFrame.label, -1, Nothing());
       } else {
         MOZ_ASSERT(jsFrame.kind == JS::ProfilingFrameIterator::Frame_Ion ||
                    jsFrame.kind == JS::ProfilingFrameIterator::Frame_Baseline);
-        aBuffer.AddEntry(
-          ProfileBufferEntry::JitReturnAddr(jsFrames[jsIndex].returnAddress));
+        aCollector.CollectJitReturnAddr(jsFrames[jsIndex].returnAddress);
       }
 
       jsIndex--;
       continue;
     }
 
     // If we reach here, there must be a native stack entry and it must be the
     // greatest entry.
     if (nativeStackAddr) {
       MOZ_ASSERT(nativeIndex >= 0);
       void* addr = (void*)aNativeStack.mPCs[nativeIndex];
-      aBuffer.AddEntry(ProfileBufferEntry::NativeLeafAddr(addr));
+      aCollector.CollectNativeLeafAddr(addr);
     }
     if (nativeIndex >= 0) {
       nativeIndex--;
     }
   }
 
   // Update the JS context with the current profile sample buffer generation.
   //
   // Do not do this for synchronous samples, which use their own
   // ProfileBuffers instead of the global one in CorePS.
-  if (!aIsSynchronous && context) {
-    MOZ_ASSERT(aBuffer.mGeneration >= startBufferGen);
-    uint32_t lapCount = aBuffer.mGeneration - startBufferGen;
-    JS::UpdateJSContextProfilerSampleBufferGen(context, aBuffer.mGeneration,
+  if (!aIsSynchronous && context && aCollector.Generation().isSome()) {
+    MOZ_ASSERT(*aCollector.Generation() >= startBufferGen);
+    uint32_t lapCount = *aCollector.Generation() - startBufferGen;
+    JS::UpdateJSContextProfilerSampleBufferGen(context,
+                                               *aCollector.Generation(),
                                                lapCount);
   }
 }
 
 #if defined(GP_OS_windows)
 static uintptr_t GetThreadHandle(PlatformData* aData);
 #endif
 
@@ -960,16 +978,18 @@ StackWalkCallback(uint32_t aFrameNumber,
   nativeStack->mCount++;
 }
 
 static void
 DoNativeBacktrace(PSLockRef aLock, const ThreadInfo& aThreadInfo,
                   const Registers& aRegs, NativeStack& aNativeStack)
 {
   // WARNING: this function runs within the profiler's "critical section".
+  // WARNING: this function might be called while the profiler is inactive, and
+  //          cannot rely on ActivePS.
 
   // Start with the current function. We use 0 as the frame number here because
   // the FramePointerStackWalk() and MozStackWalk() calls below will use 1..N.
   // This is a bit weird but it doesn't matter because StackWalkCallback()
   // doesn't use the frame number argument.
   StackWalkCallback(/* frameNum */ 0, aRegs.mPC, aRegs.mSP, &aNativeStack);
 
   uint32_t maxFrames = uint32_t(MAX_NATIVE_FRAMES - aNativeStack.mCount);
@@ -993,16 +1013,18 @@ DoNativeBacktrace(PSLockRef aLock, const
 #endif
 
 #ifdef USE_EHABI_STACKWALK
 static void
 DoNativeBacktrace(PSLockRef aLock, const ThreadInfo& aThreadInfo,
                   const Registers& aRegs, NativeStack& aNativeStack)
 {
   // WARNING: this function runs within the profiler's "critical section".
+  // WARNING: this function might be called while the profiler is inactive, and
+  //          cannot rely on ActivePS.
 
   const mcontext_t* mcontext = &aRegs.mContext->uc_mcontext;
   mcontext_t savedContext;
   NotNull<RacyThreadInfo*> racyInfo = aThreadInfo.RacyInfo();
 
   // The pseudostack contains an "EnterJIT" frame whenever we enter
   // JIT code with profiling enabled; the stack pointer value points
   // the saved registers.  We use this to unwind resume unwinding
@@ -1072,16 +1094,18 @@ ASAN_memcpy(void* aDst, const void* aSrc
 }
 #endif
 
 static void
 DoNativeBacktrace(PSLockRef aLock, const ThreadInfo& aThreadInfo,
                   const Registers& aRegs, NativeStack& aNativeStack)
 {
   // WARNING: this function runs within the profiler's "critical section".
+  // WARNING: this function might be called while the profiler is inactive, and
+  //          cannot rely on ActivePS.
 
   const mcontext_t* mc = &aRegs.mContext->uc_mcontext;
 
   lul::UnwindRegs startRegs;
   memset(&startRegs, 0, sizeof(startRegs));
 
 #if defined(GP_PLAT_amd64_linux)
   startRegs.xip = lul::TaggedUWord(mc->gregs[REG_RIP]);
@@ -1217,23 +1241,23 @@ DoSharedSample(PSLockRef aLock, bool aIs
   TimeDuration delta = aNow - CorePS::ProcessStartTime();
   aBuffer.AddEntry(ProfileBufferEntry::Time(delta.ToMilliseconds()));
 
   NativeStack nativeStack;
 #if defined(HAVE_NATIVE_UNWIND)
   if (ActivePS::FeatureStackWalk(aLock)) {
     DoNativeBacktrace(aLock, aThreadInfo, aRegs, nativeStack);
 
-    MergeStacksIntoProfile(aLock, aIsSynchronous, aThreadInfo, aRegs,
-                           nativeStack, aBuffer);
+    MergeStacks(ActivePS::Features(aLock), aIsSynchronous, aThreadInfo, aRegs,
+                nativeStack, aBuffer);
   } else
 #endif
   {
-    MergeStacksIntoProfile(aLock, aIsSynchronous, aThreadInfo, aRegs,
-                           nativeStack, aBuffer);
+    MergeStacks(ActivePS::Features(aLock), aIsSynchronous, aThreadInfo, aRegs,
+                nativeStack, aBuffer);
 
     if (ActivePS::FeatureLeaf(aLock)) {
       aBuffer.AddEntry(ProfileBufferEntry::NativeLeafAddr((void*)aRegs.mPC));
     }
   }
 }
 
 // Writes the components of a synchronous sample to the given ProfileBuffer.
@@ -3041,10 +3065,67 @@ profiler_suspend_and_sample_thread(
       // NOTE: Make sure to disable the sampler before it is destroyed, in case
       // the profiler is running at the same time.
       sampler.Disable(lock);
       break;
     }
   }
 }
 
+// NOTE: aCollector's methods will be called while the target thread is paused.
+// Doing things in those methods like allocating -- which may try to claim
+// locks -- is a surefire way to deadlock.
+void
+profiler_suspend_and_sample_thread(int aThreadId,
+                                   uint32_t aFeatures,
+                                   ProfilerStackCollector& aCollector,
+                                   bool aSampleNative /* = true */)
+{
+  // Lock the profiler mutex
+  PSAutoLock lock(gPSMutex);
+
+  const CorePS::ThreadVector& liveThreads = CorePS::LiveThreads(lock);
+  for (uint32_t i = 0; i < liveThreads.size(); i++) {
+    ThreadInfo* info = liveThreads.at(i);
+
+    if (info->ThreadId() == aThreadId) {
+      if (info->IsMainThread()) {
+        aCollector.SetIsMainThread();
+      }
+
+      // Allocate the space for the native stack
+      NativeStack nativeStack;
+
+      // Suspend, sample, and then resume the target thread.
+      Sampler sampler(lock);
+      sampler.SuspendAndSampleAndResumeThread(lock, *info,
+                                              [&](const Registers& aRegs) {
+        // The target thread is now suspended. Collect a native backtrace, and
+        // call the callback.
+        bool isSynchronous = false;
+#if defined(HAVE_NATIVE_UNWIND)
+        if (aSampleNative) {
+          DoNativeBacktrace(lock, *info, aRegs, nativeStack);
+
+          MergeStacks(aFeatures, isSynchronous, *info, aRegs, nativeStack,
+                      aCollector);
+        } else
+#endif
+        {
+          MergeStacks(aFeatures, isSynchronous, *info, aRegs, nativeStack,
+                      aCollector);
+
+          if (ProfilerFeature::HasLeaf(aFeatures)) {
+            aCollector.CollectNativeLeafAddr((void*)aRegs.mPC);
+          }
+        }
+      });
+
+      // NOTE: Make sure to disable the sampler before it is destroyed, in case
+      // the profiler is running at the same time.
+      sampler.Disable(lock);
+      break;
+    }
+  }
+}
+
 // END externally visible functions
 ////////////////////////////////////////////////////////////////////////

--- a/tools/profiler/moz.build
+++ b/tools/profiler/moz.build
@@ -76,16 +76,17 @@ if CONFIG['MOZ_GECKO_PROFILER']:
             'core/shared-libraries-macos.cc',
         ]
     elif CONFIG['OS_TARGET'] == 'WINNT':
         SOURCES += [
             'core/shared-libraries-win32.cc',
         ]
 
     LOCAL_INCLUDES += [
+        '/caps',
         '/docshell/base',
         '/ipc/chromium/src',
         '/mozglue/linker',
         '/toolkit/crashreporter/google-breakpad/src',
         '/tools/profiler/core/',
         '/tools/profiler/gecko/',
         '/xpcom/base',
     ]

--- a/tools/profiler/public/GeckoProfiler.h
+++ b/tools/profiler/public/GeckoProfiler.h
@@ -20,16 +20,17 @@
 #include <signal.h>
 #include <stdarg.h>
 #include <stdint.h>
 #include <stdlib.h>
 
 #include "mozilla/Assertions.h"
 #include "mozilla/Attributes.h"
 #include "mozilla/GuardObjects.h"
+#include "mozilla/Maybe.h"
 #include "mozilla/Sprintf.h"
 #include "mozilla/ThreadLocal.h"
 #include "mozilla/UniquePtr.h"
 #include "js/TypeDecls.h"
 #include "js/ProfilingStack.h"
 #include "nscore.h"
 
 // Make sure that we can use std::min here without the Windows headers messing
@@ -262,21 +263,62 @@ PROFILER_FUNC(int profiler_current_threa
 typedef void ProfilerStackCallback(void** aPCs, size_t aCount, bool aIsMainThread);
 
 // This method suspends the thread identified by aThreadId, optionally samples
 // it for its native stack, and then calls the callback.
 //
 // WARNING: The target thread is suspended during the callback. Do not try to
 // allocate or acquire any locks, or you could deadlock. The target thread will
 // have resumed by the time this function returns.
+//
+// XXX: this function is in the process of being replaced with the other profiler_suspend_and_sample_thread() function.
 PROFILER_FUNC_VOID(
   profiler_suspend_and_sample_thread(int aThreadId,
                                      const std::function<ProfilerStackCallback>& aCallback,
                                      bool aSampleNative = true))
 
+// An object of this class is passed to profiler_suspend_and_sample_thread().
+// For each stack frame, one of the Collect methods will be called.
+class ProfilerStackCollector
+{
+public:
+  // Some collectors need to worry about possibly overwriting previous
+  // generations of data. If that's not an issue, this can return Nothing,
+  // which is the default behaviour.
+  virtual mozilla::Maybe<uint32_t> Generation() { return mozilla::Nothing(); }
+
+  // This method will be called once if the thread being suspended is the main
+  // thread. Default behaviour is to do nothing.
+  virtual void SetIsMainThread() {}
+
+  // WARNING: The target thread is suspended when the Collect methods are
+  // called. Do not try to allocate or acquire any locks, or you could
+  // deadlock. The target thread will have resumed by the time this function
+  // returns.
+
+  virtual void CollectNativeLeafAddr(void* aAddr) = 0;
+
+  virtual void CollectJitReturnAddr(void* aAddr) = 0;
+
+  // aLabel is static and never null. aStr may be null. aLineNumber may be -1.
+  virtual void CollectCodeLocation(
+    const char* aLabel, const char* aStr, int aLineNumber,
+    const mozilla::Maybe<js::ProfileEntry::Category>& aCategory) = 0;
+};
+
+// This method suspends the thread identified by aThreadId, samples its
+// pseudo-stack, JS stack, and (optionally) native stack, passing the collected
+// frames into aCollector. aFeatures dictates which compiler features are used.
+// |Privacy| and |Leaf| are the only relevant ones.
+PROFILER_FUNC_VOID(
+  profiler_suspend_and_sample_thread(int aThreadId,
+                                     uint32_t aFeatures,
+                                     ProfilerStackCollector& aCollector,
+                                     bool aSampleNative = true))
+
 struct ProfilerBacktraceDestructor
 {
 #ifdef MOZ_GECKO_PROFILER
   void operator()(ProfilerBacktrace*);
 #else
   void operator()(ProfilerBacktrace*) {}
 #endif
 };

--- a/tools/profiler/tests/gtest/GeckoProfiler.cpp
+++ b/tools/profiler/tests/gtest/GeckoProfiler.cpp
@@ -659,8 +659,75 @@ TEST(GeckoProfiler, Bug1355807)
 
   // In bug 1355807 this caused an assertion failure in StopJSSampling().
   profiler_start(PROFILER_DEFAULT_ENTRIES, PROFILER_DEFAULT_INTERVAL,
                  features,
                  fewThreadsFilter, MOZ_ARRAY_LENGTH(fewThreadsFilter));
 
   profiler_stop();
 }
+
+class GTestStackCollector final : public ProfilerStackCollector
+{
+public:
+  GTestStackCollector()
+    : mSetIsMainThread(0)
+    , mFrames(0)
+  {}
+
+  virtual void SetIsMainThread() { mSetIsMainThread++; }
+
+  virtual void CollectNativeLeafAddr(void* aAddr) { mFrames++; }
+  virtual void CollectJitReturnAddr(void* aAddr) { mFrames++; }
+  virtual void CollectCodeLocation(
+    const char* aLabel, const char* aStr, int aLineNumber,
+    const mozilla::Maybe<js::ProfileEntry::Category>& aCategory) { mFrames++; }
+
+  int mSetIsMainThread;
+  int mFrames;
+};
+
+void DoSuspendAndSample(int aTid, nsIThread* aThread)
+{
+  aThread->Dispatch(
+    NS_NewRunnableFunction(
+      "GeckoProfiler_SuspendAndSample_Test::TestBody",
+      [&]() {
+        uint32_t features = ProfilerFeature::Leaf;
+        GTestStackCollector collector;
+        profiler_suspend_and_sample_thread(aTid, features, collector,
+                                           /* sampleNative = */ true);
+
+        ASSERT_TRUE(collector.mSetIsMainThread == 1);
+        ASSERT_TRUE(collector.mFrames > 5); // approximate; must be > 0
+      }),
+    NS_DISPATCH_SYNC);
+}
+
+TEST(GeckoProfiler, SuspendAndSample)
+{
+  nsCOMPtr<nsIThread> thread;
+  nsresult rv = NS_NewNamedThread("GeckoProfGTest", getter_AddRefs(thread));
+  ASSERT_TRUE(NS_SUCCEEDED(rv));
+
+  int tid = Thread::GetCurrentId();
+
+  ASSERT_TRUE(!profiler_is_active());
+
+  // Suspend and sample while the profiler is inactive.
+  DoSuspendAndSample(tid, thread);
+
+  uint32_t features = ProfilerFeature::JS | ProfilerFeature::Threads;
+  const char* filters[] = { "GeckoMain", "Compositor" };
+
+  profiler_start(PROFILER_DEFAULT_ENTRIES, PROFILER_DEFAULT_INTERVAL,
+                 features, filters, MOZ_ARRAY_LENGTH(filters));
+
+  ASSERT_TRUE(profiler_is_active());
+
+  // Suspend and sample while the profiler is active.
+  DoSuspendAndSample(tid, thread);
+
+  profiler_stop();
+
+  ASSERT_TRUE(!profiler_is_active());
+}
+