--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -49,16 +49,17 @@
 #include "nsIScriptError.h"
 #include "nsIConsoleService.h"
 #include "nsJSEnvironment.h"
 #include "SandboxHal.h"
 #include "nsDebugImpl.h"
 #include "nsHashPropertyBag.h"
 #include "nsLayoutStylesheetCache.h"
 #include "nsIJSRuntimeService.h"
+#include "nsThreadManager.h"
 
 #include "IHistory.h"
 #include "nsNetUtil.h"
 
 #include "base/message_loop.h"
 #include "base/process_util.h"
 #include "base/task.h"
 
@@ -335,16 +336,24 @@ ContentChild::Init(MessageLoop* aIOLoop,
 #endif
 
 #ifdef MOZ_NUWA_PROCESS
     SetTransport(aChannel);
 #endif
 
     NS_ASSERTION(!sSingleton, "only one ContentChild per child");
 
+    // Once we start sending IPC messages, we need the thread manager to be
+    // initialized so we can deal with the responses. Do that here before we
+    // try to construct the crash reporter.
+    nsresult rv = nsThreadManager::get()->Init();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+        return false;
+    }
+
     Open(aChannel, aParentHandle, aIOLoop);
     sSingleton = this;
 
 #ifdef MOZ_CRASHREPORTER
     SendPCrashReporterConstructor(CrashReporter::CurrentThreadId(),
                                   XRE_GetProcessType());
 #endif
 

--- a/dom/ipc/moz.build
+++ b/dom/ipc/moz.build
@@ -101,16 +101,17 @@ LOCAL_INCLUDES += [
     '/hal/sandbox',
     '/js/ipc',
     '/layout/base',
     '/netwerk/base/src',
     '/toolkit/xre',
     '/uriloader/exthandler',
     '/widget/xpwidgets',
     '/xpcom/base',
+    '/xpcom/threads',
 ]
 
 DEFINES['BIN_SUFFIX'] = '"%s"' % CONFIG['BIN_SUFFIX']
 
 if CONFIG['MOZ_WIDGET_TOOLKIT'] in ('android', 'gtk2', 'gonk', 'qt'):
     DEFINES['MOZ_ENABLE_FREETYPE'] = True
 
 for var in ('MOZ_PERMISSIONS', 'MOZ_CHILD_PERMISSIONS'):

--- a/xpcom/threads/nsThreadManager.cpp
+++ b/xpcom/threads/nsThreadManager.cpp
@@ -51,34 +51,38 @@ NS_IMPL_CLASSINFO(nsThreadManager, nullp
 NS_IMPL_QUERY_INTERFACE1_CI(nsThreadManager, nsIThreadManager)
 NS_IMPL_CI_INTERFACE_GETTER1(nsThreadManager, nsIThreadManager)
 
 //-----------------------------------------------------------------------------
 
 nsresult
 nsThreadManager::Init()
 {
+  // Child processes need to initialize the thread manager before they
+  // initialize XPCOM in order to set up the crash reporter. This leads to
+  // situations where we get initialized twice.
+  if (mInitialized)
+    return NS_OK;
+
   if (PR_NewThreadPrivateIndex(&mCurThreadIndex, ReleaseObject) == PR_FAILURE)
     return NS_ERROR_FAILURE;
 
   mLock = new Mutex("nsThreadManager.mLock");
 
 #ifdef MOZ_CANARY
   const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
   const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
   char* env_var_flag = getenv("MOZ_KILL_CANARIES");
   sCanaryOutputFD = env_var_flag ? (env_var_flag[0] ?
       open(env_var_flag, flags, mode) :
       STDERR_FILENO) : 0;
 #endif
 
   // Setup "main" thread
   mMainThread = new nsThread(nsThread::MAIN_THREAD, 0);
-  if (!mMainThread)
-    return NS_ERROR_OUT_OF_MEMORY;
 
   nsresult rv = mMainThread->InitCurrentThread();
   if (NS_FAILED(rv)) {
     mMainThread = nullptr;
     return rv;
   }
 
   // We need to keep a pointer to the current thread, so we can satisfy