diff -r 000000000000 -r 6474c204b198 widget/gonk/WidgetTraceEvent.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/widget/gonk/WidgetTraceEvent.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,96 @@
+/* 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 "mozilla/WidgetTraceEvent.h"
+#include "mozilla/StaticPtr.h"
+#include "nsThreadUtils.h"
+#include <mozilla/CondVar.h>
+#include <mozilla/Mutex.h>
+
+using mozilla::CondVar;
+using mozilla::Mutex;
+using mozilla::MutexAutoLock;
+
+namespace mozilla {
+  class TracerRunnable : public nsRunnable {
+    public:
+      TracerRunnable() {
+        mTracerLock = new Mutex("TracerRunnable");
+        mTracerCondVar = new CondVar(*mTracerLock, "TracerRunnable");
+        mMainThread = do_GetMainThread();
+      }
+
+      ~TracerRunnable() {
+        delete mTracerCondVar;
+        delete mTracerLock;
+        mTracerLock = nullptr;
+        mTracerCondVar = nullptr;
+      }
+
+      virtual nsresult Run() {
+        MutexAutoLock lock(*mTracerLock);
+        mHasRun = true;
+        mTracerCondVar->Notify();
+        return NS_OK;
+      }
+
+      bool Fire() {
+        if (!mTracerLock || !mTracerCondVar) {
+          return false;
+        }
+
+        MutexAutoLock lock(*mTracerLock);
+        mHasRun = false;
+        mMainThread->Dispatch(this, NS_DISPATCH_NORMAL);
+        while (!mHasRun) {
+          mTracerCondVar->Wait();
+        }
+        return true;
+      }
+
+      void Signal() {
+        MutexAutoLock lock(*mTracerLock);
+        mHasRun = true;
+        mTracerCondVar->Notify();
+      }
+
+    private:
+      Mutex* mTracerLock;
+      CondVar* mTracerCondVar;
+      bool mHasRun;
+      nsCOMPtr<nsIThread> mMainThread;
+  };
+
+  StaticRefPtr<TracerRunnable> sTracerRunnable;
+
+  bool InitWidgetTracing()
+  {
+    if (!sTracerRunnable) {
+      sTracerRunnable = new TracerRunnable();
+    }
+    return true;
+  }
+
+  void CleanUpWidgetTracing()
+  {
+    sTracerRunnable = nullptr;
+  }
+
+  bool FireAndWaitForTracerEvent()
+  {
+    if (sTracerRunnable) {
+      return sTracerRunnable->Fire();
+    }
+
+    return false;
+  }
+
+  void SignalTracerThread()
+  {
+    if (sTracerRunnable) {
+      return sTracerRunnable->Signal();
+    }
+  }
+}  // namespace mozilla
+