diff -r 000000000000 -r 6474c204b198 gfx/src/gfxCrashReporterUtils.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gfx/src/gfxCrashReporterUtils.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,120 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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 "gfxCrashReporterUtils.h"
+
+#if defined(MOZ_CRASHREPORTER)
+#define MOZ_GFXFEATUREREPORTER 1
+#endif
+
+#ifdef MOZ_GFXFEATUREREPORTER
+#include "gfxCrashReporterUtils.h"
+#include <string.h>                     // for strcmp
+#include "mozilla/Assertions.h"         // for MOZ_ASSERT_HELPER2
+#include "mozilla/Services.h"           // for GetObserverService
+#include "mozilla/mozalloc.h"           // for operator new, etc
+#include "nsAutoPtr.h"                  // for nsRefPtr
+#include "nsCOMPtr.h"                   // for nsCOMPtr
+#include "nsError.h"                    // for NS_OK, NS_FAILED, nsresult
+#include "nsExceptionHandler.h"         // for AppendAppNotesToCrashReport
+#include "nsID.h"
+#include "nsIEventTarget.h"             // for NS_DISPATCH_NORMAL
+#include "nsIObserver.h"                // for nsIObserver, etc
+#include "nsIObserverService.h"         // for nsIObserverService
+#include "nsIRunnable.h"                // for nsIRunnable
+#include "nsISupports.h"
+#include "nsString.h"               // for nsAutoCString, nsCString, etc
+#include "nsTArray.h"                   // for nsTArray
+#include "nsThreadUtils.h"              // for NS_DispatchToMainThread, etc
+#include "nscore.h"                     // for NS_IMETHOD, NS_IMETHODIMP, etc
+
+namespace mozilla {
+
+static nsTArray<nsCString> *gFeaturesAlreadyReported = nullptr;
+
+class ObserverToDestroyFeaturesAlreadyReported : public nsIObserver
+{
+
+public:
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSIOBSERVER
+
+  ObserverToDestroyFeaturesAlreadyReported() {}
+  virtual ~ObserverToDestroyFeaturesAlreadyReported() {}
+};
+
+NS_IMPL_ISUPPORTS(ObserverToDestroyFeaturesAlreadyReported,
+                  nsIObserver)
+
+NS_IMETHODIMP
+ObserverToDestroyFeaturesAlreadyReported::Observe(nsISupports* aSubject,
+                                                  const char* aTopic,
+                                                  const char16_t* aData)
+{
+  if (!strcmp(aTopic, "xpcom-shutdown")) {
+    if (gFeaturesAlreadyReported) {
+      delete gFeaturesAlreadyReported;
+      gFeaturesAlreadyReported = nullptr;
+    }
+  }
+  return NS_OK;
+}
+
+class ScopedGfxFeatureReporter::AppNoteWritingRunnable : public nsRunnable {
+public:
+  AppNoteWritingRunnable(char aStatusChar, const char *aFeature) :
+    mStatusChar(aStatusChar), mFeature(aFeature) {}
+  NS_IMETHOD Run() { 
+    // LeakLog made me do this. Basically, I just wanted gFeaturesAlreadyReported to be a static nsTArray<nsCString>,
+    // and LeakLog was complaining about leaks like this:
+    //    leaked 1 instance of nsTArray_base with size 8 bytes
+    //    leaked 7 instances of nsStringBuffer with size 8 bytes each (56 bytes total)
+    // So this is a work-around using a pointer, and using a nsIObserver to deallocate on xpcom shutdown.
+    // Yay for fighting bloat.
+    if (!gFeaturesAlreadyReported) {
+      nsCOMPtr<nsIObserverService> observerService = mozilla::services::GetObserverService();
+      if (!observerService)
+        return NS_OK;
+      nsRefPtr<ObserverToDestroyFeaturesAlreadyReported> observer = new ObserverToDestroyFeaturesAlreadyReported;
+      nsresult rv = observerService->AddObserver(observer, "xpcom-shutdown", false);
+      if (NS_FAILED(rv)) {
+        observer = nullptr;
+        return NS_OK;
+      }
+      gFeaturesAlreadyReported = new nsTArray<nsCString>;
+    }
+
+    nsAutoCString featureString;
+    featureString.AppendPrintf("%s%c ",
+                               mFeature,
+                               mStatusChar);
+
+    if (!gFeaturesAlreadyReported->Contains(featureString)) {
+      gFeaturesAlreadyReported->AppendElement(featureString);
+      CrashReporter::AppendAppNotesToCrashReport(featureString);
+    }
+    return NS_OK;
+  }
+private:
+  char mStatusChar;
+  const char *mFeature;
+};
+
+void
+ScopedGfxFeatureReporter::WriteAppNote(char statusChar)
+{
+  nsCOMPtr<nsIRunnable> r = new AppNoteWritingRunnable(statusChar, mFeature);
+  NS_DispatchToMainThread(r.get(), NS_DISPATCH_NORMAL);
+}
+
+} // end namespace mozilla
+
+#else
+
+namespace mozilla {
+void ScopedGfxFeatureReporter::WriteAppNote(char) {}
+}
+
+#endif