Reland of Change ProcessThread's task type to be the one from TaskQueue.

webrtc/modules/utility/include/mock/mock_process_thread.h

Index: webrtc/modules/utility/include/mock/mock_process_thread.h
diff --git a/webrtc/modules/utility/include/mock/mock_process_thread.h b/webrtc/modules/utility/include/mock/mock_process_thread.h
index 621fcee818249bef6fdd221ca4f37d49c5b5ef0d..c6520bb20f1a55e4b1859ecd97693f24845cf9a6 100644
--- a/webrtc/modules/utility/include/mock/mock_process_thread.h
+++ b/webrtc/modules/utility/include/mock/mock_process_thread.h
@@ -28,14 +28,14 @@
   MOCK_METHOD0(Start, void());
   MOCK_METHOD0(Stop, void());
   MOCK_METHOD1(WakeUp, void(Module* module));
-  MOCK_METHOD1(PostTask, void(ProcessTask* task));
+  MOCK_METHOD1(PostTask, void(rtc::QueuedTask* task));
   MOCK_METHOD1(RegisterModule, void(Module* module));
   MOCK_METHOD1(DeRegisterModule, void(Module* module));
 
   // MOCK_METHOD1 gets confused with mocking this method, so we work around it
   // by overriding the method from the interface and forwarding the call to a
   // mocked, simpler method.
-  void PostTask(std::unique_ptr<ProcessTask> task) /* override */ {
+  void PostTask(std::unique_ptr<rtc::QueuedTask> task) /*override*/ {
     PostTask(task.get());
   }
 };