--- a/dom/ipc/ContentChild.cpp
+++ b/dom/ipc/ContentChild.cpp
@@ -189,16 +189,17 @@
 #ifdef XP_WIN
 #include <process.h>
 #define getpid _getpid
 #include "mozilla/widget/AudioSession.h"
 #include "mozilla/audio/AudioNotificationReceiver.h"
 #endif
 
 #if defined(XP_MACOSX)
+#include "nsMacUtilsImpl.h"
 #include <CoreServices/CoreServices.h>
 // Info.plist key associated with the developer repo path
 #define MAC_DEV_REPO_KEY "MozillaDeveloperRepoPath"
 // Info.plist key associated with the developer repo object directory
 #define MAC_DEV_OBJ_KEY "MozillaDeveloperObjPath"
 #endif /* XP_MACOSX */
 
 #ifdef MOZ_X11
@@ -1518,120 +1519,16 @@ ContentChild::RecvReinitRenderingForDevi
     if (tabChild->GetLayersId().IsValid()) {
       tabChild->ReinitRenderingForDeviceReset();
     }
   }
   return IPC_OK();
 }
 
 #if defined(XP_MACOSX) && defined(MOZ_CONTENT_SANDBOX)
-
-#include <stdlib.h>
-
-static bool
-GetAppPaths(nsCString &aAppPath, nsCString &aAppBinaryPath, nsCString &aAppDir)
-{
-  nsAutoCString appPath;
-  nsAutoCString appBinaryPath(
-    (CommandLine::ForCurrentProcess()->argv()[0]).c_str());
-
-  nsAutoCString::const_iterator start, end;
-  appBinaryPath.BeginReading(start);
-  appBinaryPath.EndReading(end);
-  if (RFindInReadable(NS_LITERAL_CSTRING(".app/Contents/MacOS/"), start, end)) {
-    end = start;
-    ++end; ++end; ++end; ++end;
-    appBinaryPath.BeginReading(start);
-    appPath.Assign(Substring(start, end));
-  } else {
-    return false;
-  }
-
-  nsCOMPtr<nsIFile> app, appBinary;
-  nsresult rv = NS_NewLocalFile(NS_ConvertUTF8toUTF16(appPath),
-                                true, getter_AddRefs(app));
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-  rv = NS_NewLocalFile(NS_ConvertUTF8toUTF16(appBinaryPath),
-                       true, getter_AddRefs(appBinary));
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-
-  nsCOMPtr<nsIFile> appDir;
-  nsCOMPtr<nsIProperties> dirSvc =
-    do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID);
-  if (!dirSvc) {
-    return false;
-  }
-  rv = dirSvc->Get(NS_GRE_DIR,
-                   NS_GET_IID(nsIFile), getter_AddRefs(appDir));
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-  bool exists;
-  rv = appDir->Exists(&exists);
-  if (NS_FAILED(rv) || !exists) {
-    return false;
-  }
-
-  // appDir points to .app/Contents/Resources, for our purposes we want
-  // .app/Contents.
-  nsCOMPtr<nsIFile> appDirParent;
-  rv = appDir->GetParent(getter_AddRefs(appDirParent));
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-
-  rv = app->Normalize();
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-  app->GetNativePath(aAppPath);
-
-  rv = appBinary->Normalize();
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-  appBinary->GetNativePath(aAppBinaryPath);
-
-  rv = appDirParent->Normalize();
-  if (NS_FAILED(rv)) {
-    return false;
-  }
-  appDirParent->GetNativePath(aAppDir);
-
-  return true;
-}
-
-// This function is only used in an |#ifdef DEBUG| path.
-#ifdef DEBUG
-// Given a path to a file, return the directory which contains it.
-static nsAutoCString
-GetDirectoryPath(const char *aPath) {
-  nsCOMPtr<nsIFile> file = do_CreateInstance(NS_LOCAL_FILE_CONTRACTID);
-  if (!file ||
-      NS_FAILED(file->InitWithNativePath(nsDependentCString(aPath)))) {
-    MOZ_CRASH("Failed to create or init an nsIFile");
-  }
-  nsCOMPtr<nsIFile> directoryFile;
-  if (NS_FAILED(file->GetParent(getter_AddRefs(directoryFile))) ||
-      !directoryFile) {
-    MOZ_CRASH("Failed to get parent for an nsIFile");
-  }
-  directoryFile->Normalize();
-  nsAutoCString directoryPath;
-  if (NS_FAILED(directoryFile->GetNativePath(directoryPath))) {
-    MOZ_CRASH("Failed to get path for an nsIFile");
-  }
-  return directoryPath;
-}
-#endif // DEBUG
-
 extern "C" {
 CGError
 CGSSetDenyWindowServerConnections(bool);
 void CGSShutdownServerConnections();
 };
 
 static bool
 StartMacOSContentSandbox()
@@ -1654,17 +1551,17 @@ StartMacOSContentSandbox()
     CGError result = CGSSetDenyWindowServerConnections(true);
     MOZ_DIAGNOSTIC_ASSERT(result == kCGErrorSuccess);
 #if !MOZ_DIAGNOSTIC_ASSERT_ENABLED
     Unused << result;
 #endif
   }
 
   nsAutoCString appPath, appBinaryPath, appDir;
-  if (!GetAppPaths(appPath, appBinaryPath, appDir)) {
+  if (!nsMacUtilsImpl::GetAppPaths(appPath, appBinaryPath, appDir)) {
     MOZ_CRASH("Error resolving child process path");
   }
 
   ContentChild* cc = ContentChild::GetSingleton();
 
   nsresult rv;
   nsCOMPtr<nsIFile> profileDir;
   cc->GetProfileDir(getter_AddRefs(profileDir));
@@ -1737,17 +1634,18 @@ StartMacOSContentSandbox()
 #ifdef DEBUG
   // When a content process dies intentionally (|NoteIntentionalCrash|), for
   // tests it wants to log that it did this. Allow writing to this location
   // that the testrunner wants.
   char *bloatLog = PR_GetEnv("XPCOM_MEM_BLOAT_LOG");
   if (bloatLog != nullptr) {
     // |bloatLog| points to a specific file, but we actually write to a sibling
     // of that path.
-    nsAutoCString bloatDirectoryPath = GetDirectoryPath(bloatLog);
+    nsAutoCString bloatDirectoryPath =
+      nsMacUtilsImpl::GetDirectoryPath(bloatLog);
     info.debugWriteDir.assign(bloatDirectoryPath.get());
   }
 #endif // DEBUG
 
   std::string err;
   if (!mozilla::StartMacSandbox(info, err)) {
     NS_WARNING(err.c_str());
     MOZ_CRASH("sandbox_init() failed");

--- a/xpcom/base/nsMacUtilsImpl.cpp
+++ b/xpcom/base/nsMacUtilsImpl.cpp
@@ -1,16 +1,23 @@
 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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 "nsMacUtilsImpl.h"
 
+#include "base/command_line.h"
+#include "nsDirectoryServiceDefs.h"
+#include "nsCOMPtr.h"
+#include "nsIFile.h"
+#include "nsIProperties.h"
+#include "nsServiceManagerUtils.h"
+
 #include <CoreFoundation/CoreFoundation.h>
 
 NS_IMPL_ISUPPORTS(nsMacUtilsImpl, nsIMacUtils)
 
 nsresult
 nsMacUtilsImpl::GetArchString(nsAString& aArchString)
 {
   if (!mBinaryArchs.IsEmpty()) {
@@ -120,8 +127,113 @@ nsMacUtilsImpl::GetIsTranslated(bool* aI
 #else
   // Translation only exists for ppc code.  Other architectures aren't
   // translated.
   *aIsTranslated = false;
 #endif
 
   return NS_OK;
 }
+
+#if defined(MOZ_CONTENT_SANDBOX)
+bool
+nsMacUtilsImpl::GetAppPaths(nsCString &aAppPath,
+                            nsCString &aAppBinaryPath,
+                            nsCString &aAppDir)
+{
+  nsAutoCString appPath;
+  nsAutoCString appBinaryPath(
+    (CommandLine::ForCurrentProcess()->argv()[0]).c_str());
+
+  nsAutoCString::const_iterator start, end;
+  appBinaryPath.BeginReading(start);
+  appBinaryPath.EndReading(end);
+  if (RFindInReadable(NS_LITERAL_CSTRING(".app/Contents/MacOS/"), start, end)) {
+    end = start;
+    ++end; ++end; ++end; ++end;
+    appBinaryPath.BeginReading(start);
+    appPath.Assign(Substring(start, end));
+  } else {
+    return false;
+  }
+
+  nsCOMPtr<nsIFile> app, appBinary;
+  nsresult rv = NS_NewLocalFile(NS_ConvertUTF8toUTF16(appPath),
+                                true, getter_AddRefs(app));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  rv = NS_NewLocalFile(NS_ConvertUTF8toUTF16(appBinaryPath),
+                       true, getter_AddRefs(appBinary));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  nsCOMPtr<nsIFile> appDir;
+  nsCOMPtr<nsIProperties> dirSvc =
+    do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID);
+  if (!dirSvc) {
+    return false;
+  }
+  rv = dirSvc->Get(NS_GRE_DIR,
+                   NS_GET_IID(nsIFile), getter_AddRefs(appDir));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  bool exists;
+  rv = appDir->Exists(&exists);
+  if (NS_FAILED(rv) || !exists) {
+    return false;
+  }
+
+  // appDir points to .app/Contents/Resources, for our purposes we want
+  // .app/Contents.
+  nsCOMPtr<nsIFile> appDirParent;
+  rv = appDir->GetParent(getter_AddRefs(appDirParent));
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+
+  rv = app->Normalize();
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  app->GetNativePath(aAppPath);
+
+  rv = appBinary->Normalize();
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  appBinary->GetNativePath(aAppBinaryPath);
+
+  rv = appDirParent->Normalize();
+  if (NS_FAILED(rv)) {
+    return false;
+  }
+  appDirParent->GetNativePath(aAppDir);
+
+  return true;
+}
+
+#if defined(DEBUG)
+// Given a path to a file, return the directory which contains it.
+nsAutoCString
+nsMacUtilsImpl::GetDirectoryPath(const char *aPath)
+{
+  nsCOMPtr<nsIFile> file = do_CreateInstance(NS_LOCAL_FILE_CONTRACTID);
+  if (!file ||
+      NS_FAILED(file->InitWithNativePath(nsDependentCString(aPath)))) {
+    MOZ_CRASH("Failed to create or init an nsIFile");
+  }
+  nsCOMPtr<nsIFile> directoryFile;
+  if (NS_FAILED(file->GetParent(getter_AddRefs(directoryFile))) ||
+      !directoryFile) {
+    MOZ_CRASH("Failed to get parent for an nsIFile");
+  }
+  directoryFile->Normalize();
+  nsAutoCString directoryPath;
+  if (NS_FAILED(directoryFile->GetNativePath(directoryPath))) {
+    MOZ_CRASH("Failed to get path for an nsIFile");
+  }
+  return directoryPath;
+}
+#endif /* DEBUG */
+#endif /* MOZ_CONTENT_SANDBOX */

--- a/xpcom/base/nsMacUtilsImpl.h
+++ b/xpcom/base/nsMacUtilsImpl.h
@@ -16,16 +16,26 @@ class nsMacUtilsImpl final : public nsIM
 public:
   NS_DECL_ISUPPORTS
   NS_DECL_NSIMACUTILS
 
   nsMacUtilsImpl()
   {
   }
 
+#if defined(MOZ_CONTENT_SANDBOX)
+  static bool GetAppPaths(nsCString &aAppPath,
+                          nsCString &aAppBinaryPath,
+                          nsCString &aAppDir);
+
+#ifdef DEBUG
+  static nsAutoCString GetDirectoryPath(const char *aPath);
+#endif /* DEBUG */
+#endif /* MOZ_CONTENT_SANDBOX */
+
 private:
   ~nsMacUtilsImpl()
   {
   }
 
   nsresult GetArchString(nsAString& aArchString);
 
   // A string containing a "-" delimited list of architectures