Add ChildMessageFilter, a base class for renderer/worker cross-thread MessageFilter

content/child/quota_message_filter.h

Index: content/child/quota_message_filter.h
diff --git a/content/child/quota_message_filter.h b/content/child/quota_message_filter.h
index eba63137dfe451b038281ae31f87d8008a9c7e95..dccadd5fd2068d8a0fecdb02af950612b4e6d2de 100644
--- a/content/child/quota_message_filter.h
+++ b/content/child/quota_message_filter.h
@@ -8,23 +8,16 @@
 #include <map>
 
 #include "base/synchronization/lock.h"
-#include "ipc/ipc_channel_proxy.h"
-
-namespace base {
-class MessageLoopProxy;
-}
+#include "content/child/cross_thread_message_filter.h"
 
 namespace content {
 
 class ThreadSafeSender;
 
-class QuotaMessageFilter : public IPC::ChannelProxy::MessageFilter {
+class QuotaMessageFilter : public CrossThreadMessageFilter {
  public:
   explicit QuotaMessageFilter(ThreadSafeSender* thread_safe_sender);
 
-  // IPC::Listener implementation.
-  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
-
   // Generates a new request_id, registers { request_id, thread_id } map to
   // the message filter and returns the request_id.
   // This method can be called on any thread.
@@ -37,11 +30,13 @@ class QuotaMessageFilter : public IPC::ChannelProxy::MessageFilter {
   virtual ~QuotaMessageFilter();
 
  private:
-  typedef std::map<int, int> RequestIdToThreadId;
+  // CrossThreadMessageFilter implementation:
+  virtual bool OverrideThreadIDForMessage(const IPC::Message& msg,
+                                          int* thread_id) OVERRIDE;
+  virtual bool OnMessageReceived(const IPC::Message& msg) OVERRIDE;
 
-  void DispatchMessage(const IPC::Message& msg);
+  typedef std::map<int, int> RequestIdToThreadId;
 
-  scoped_refptr<base::MessageLoopProxy> main_thread_loop_proxy_;
   scoped_refptr<ThreadSafeSender> thread_safe_sender_;
 
   base::Lock request_id_map_lock_;