Revert r21117 as it caused reliability failures....

chrome/common/child_thread.h

Index: chrome/common/child_thread.h
===================================================================
--- chrome/common/child_thread.h	(revision 21215)
+++ chrome/common/child_thread.h	(working copy)
@@ -7,20 +7,18 @@
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
+#include "base/thread.h"
 #include "chrome/common/ipc_sync_channel.h"
 #include "chrome/common/message_router.h"
 #include "chrome/common/resource_dispatcher.h"
 
-class NotificationService;
-
-// The main thread of a child process derives from this class.
+// Child processes's background thread should derive from this class.
 class ChildThread : public IPC::Channel::Listener,
-                    public IPC::Message::Sender {
+                    public IPC::Message::Sender,
+                    public base::Thread {
  public:
   // Creates the thread.
-  ChildThread();
-  // Used for single-process mode.
-  ChildThread(const std::string channel_name);
+  ChildThread(Thread::Options options);
   virtual ~ChildThread();
 
   // IPC::Message::Sender implementation:
@@ -30,39 +28,58 @@
   void AddRoute(int32 routing_id, IPC::Channel::Listener* listener);
   void RemoveRoute(int32 routing_id);
 
+  MessageLoop* owner_loop() { return owner_loop_; }
+
   ResourceDispatcher* resource_dispatcher() {
     return resource_dispatcher_.get();
   }
 
-  MessageLoop* message_loop() { return message_loop_; }
-
   // Returns the one child thread.
   static ChildThread* current();
 
  protected:
   friend class ChildProcess;
 
+  // Starts the thread.
+  bool Run();
+
+  // Overrides the channel name.  Used for --single-process mode.
+  void SetChannelName(const std::string& name) { channel_name_ = name; }
+
   // Called when the process refcount is 0.
   void OnProcessFinalRelease();
 
+ protected:
+  // The required stack size if V8 runs on a thread.
+  static const size_t kV8StackSize;
+
   virtual void OnControlMessageReceived(const IPC::Message& msg) { }
 
   IPC::SyncChannel* channel() { return channel_.get(); }
 
+  // Thread implementation.
+  virtual void Init();
+  virtual void CleanUp();
+
  private:
-  void Init();
-
   // IPC::Channel::Listener implementation:
   virtual void OnMessageReceived(const IPC::Message& msg);
   virtual void OnChannelError();
 
+  // The message loop used to run tasks on the thread that started this thread.
+  MessageLoop* owner_loop_;
+
   std::string channel_name_;
   scoped_ptr<IPC::SyncChannel> channel_;
 
-  // Implements message routing functionality to the consumers of ChildThread.
+  // Used only on the background render thread to implement message routing
+  // functionality to the consumers of the ChildThread.
   MessageRouter router_;
 
+  Thread::Options options_;
+
   // Handles resource loads for this process.
+  // NOTE: this object lives on the owner thread.
   scoped_ptr<ResourceDispatcher> resource_dispatcher_;
 
   // If true, checks with the browser process before shutdown.  This avoids race
@@ -70,10 +87,6 @@
   // that would addref it.
   bool check_with_browser_before_shutdown_;
 
-  MessageLoop* message_loop_;
-
-  scoped_ptr<NotificationService> notification_service_;
-
   DISALLOW_COPY_AND_ASSIGN(ChildThread);
 };