Created a MessageLoopProxy interface. This provides a thread-safe refcounted ...

chrome/browser/chrome_thread.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/chrome_thread.h"
 
 #include "base/message_loop.h"
+#include "base/message_loop_proxy.h"
 
 // Friendly names for the well-known threads.
 static const char* chrome_thread_names[ChromeThread::ID_COUNT] = {
   "",  // UI (name assembled in browser_main.cc).
   "Chrome_DBThread",  // DB
   "Chrome_WebKitThread",  // WEBKIT
   "Chrome_FileThread",  // FILE
   "Chrome_ProcessLauncherThread",  // PROCESS_LAUNCHER
   "Chrome_IOThread",  // IO
 #if defined(USE_X11)
   "Chrome_Background_X11Thread",  // BACKGROUND_X11
 #endif
 };
 
+// An implementation of MessageLoopProxy to be used in conjunction
+// with ChromeThread.
+class ChromeThreadMessageLoopProxy : public MessageLoopProxy {
+ public:
+  explicit ChromeThreadMessageLoopProxy(ChromeThread::ID identifier)
+      : id_(identifier) {
+  }
+
+  // MessageLoopProxy implementation.
+  virtual bool PostTask(const tracked_objects::Location& from_here,
+                        Task* task) {
+    return ChromeThread::PostTask(id_, from_here, task);
+  }
+
+  virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
+                               Task* task, int64 delay_ms) {
+    return ChromeThread::PostDelayedTask(id_, from_here, task, delay_ms);
+  }
+
+  virtual bool PostNonNestableTask(const tracked_objects::Location& from_here,
+                                   Task* task) {
+    return ChromeThread::PostNonNestableTask(id_, from_here, task);
+  }
+
+  virtual bool PostNonNestableDelayedTask(
+      const tracked_objects::Location& from_here,
+      Task* task,
+      int64 delay_ms) {
+    return ChromeThread::PostNonNestableDelayedTask(id_, from_here, task,
+                                                    delay_ms);
+  }
+
+ private:
+  ChromeThread::ID id_;
+  DISALLOW_COPY_AND_ASSIGN(ChromeThreadMessageLoopProxy);
+};
+
+
 Lock ChromeThread::lock_;
 
 ChromeThread* ChromeThread::chrome_threads_[ID_COUNT];
 
 ChromeThread::ChromeThread(ChromeThread::ID identifier)
     : Thread(chrome_thread_names[identifier]),
       identifier_(identifier) {
   Initialize();
 }
 
@@ skipping 83 matching lines @@
         chrome_threads_[i]->message_loop() == cur_message_loop) {
       *identifier = chrome_threads_[i]->identifier_;
       return true;
     }
   }
 
   return false;
 }
 
 // static
+scoped_refptr<MessageLoopProxy> ChromeThread::GetMessageLoopProxyForThread(
+    ID identifier) {
+  scoped_refptr<MessageLoopProxy> proxy =
+      new ChromeThreadMessageLoopProxy(identifier);
+  return proxy;
+}
+
+// static
 bool ChromeThread::PostTaskHelper(
     ID identifier,
     const tracked_objects::Location& from_here,
     Task* task,
     int64 delay_ms,
     bool nestable) {
   DCHECK(identifier >= 0 && identifier < ID_COUNT);
   // Optimization: to avoid unnecessary locks, we listed the ID enumeration in
   // order of lifetime.  So no need to lock if we know that the other thread
   // outlives this one.
@@ skipping 18 matching lines @@
     }
   } else {
     delete task;
   }
 
   if (!guaranteed_to_outlive_target_thread)
     lock_.Release();
 
   return !!message_loop;
 }