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

webrtc/modules/utility/source/process_thread_impl.h

Index: webrtc/modules/utility/source/process_thread_impl.h
diff --git a/webrtc/modules/utility/source/process_thread_impl.h b/webrtc/modules/utility/source/process_thread_impl.h
index 510ab52daf3651285f231aeae66be1aa0e6ad7b0..330aec946c9d9c56559d7b693a051cc4529ad618 100644
--- a/webrtc/modules/utility/source/process_thread_impl.h
+++ b/webrtc/modules/utility/source/process_thread_impl.h
@@ -33,7 +33,7 @@
   void Stop() override;
 
   void WakeUp(Module* module) override;
-  void PostTask(std::unique_ptr<rtc::QueuedTask> task) override;
+  void PostTask(std::unique_ptr<ProcessTask> task) override;
 
   void RegisterModule(Module* module) override;
   void DeRegisterModule(Module* module) override;
@@ -75,7 +75,8 @@
   std::unique_ptr<rtc::PlatformThread> thread_;
 
   ModuleList modules_;
-  std::queue<rtc::QueuedTask*> queue_;
+  // TODO(tommi): Support delayed tasks.
+  std::queue<ProcessTask*> queue_;
   bool stop_;
   const char* thread_name_;
 };