content/gpu: Simplify gpu channel message handling.

content/common/gpu/gpu_channel_manager.h

Index: content/common/gpu/gpu_channel_manager.h
diff --git a/content/common/gpu/gpu_channel_manager.h b/content/common/gpu/gpu_channel_manager.h
index 4de851abf20722e7cb08182f7a6b80901931639d..e567377bbb632268b76ea33e19e19951aa94f32a 100644
--- a/content/common/gpu/gpu_channel_manager.h
+++ b/content/common/gpu/gpu_channel_manager.h
@@ -82,9 +82,6 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
   // Sender overrides.
   bool Send(IPC::Message* msg) override;
 
-  uint32_t ProcessedOrderNumber();
-  uint32_t UnprocessedOrderNumber();
-
   void LoseAllContexts();
 
   int GenerateRouteID();
@@ -97,7 +94,7 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
 
   GpuMemoryManager* gpu_memory_manager() { return &gpu_memory_manager_; }
 
-  GpuChannel* LookupChannel(int32 client_id);
+  GpuChannel* LookupChannel(int32 client_id) const;
 
   gpu::SyncPointManager* sync_point_manager() {
     return sync_point_manager_;
@@ -109,6 +106,17 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
     return gpu_memory_buffer_factory_;
   }
 
+  // Increments the global order number used for IPC messages and returns the
+  // new value.
+  uint32_t GetNextUnprocessedOrderNum();
+
+  // Returns the current value of the global order number used for IPC messages.
+  uint32_t GetCurrentUnprocessedOrderNum() const;
+
+  // Returns the maximum order number for processed IPC messages across all
+  // channels.
+  uint32_t GetProcessedOrderNum() const;
+
  protected:
   virtual scoped_ptr<GpuChannel> CreateGpuChannel(
       gfx::GLShareGroup* share_group,
@@ -177,6 +185,9 @@ class CONTENT_EXPORT GpuChannelManager : public IPC::Listener,
   // Must outlive this instance of GpuChannelManager.
   IPC::AttachmentBroker* attachment_broker_;
 
+  uint32_t unprocessed_order_num_;
+  mutable base::Lock order_num_lock_;  // Guards unprocessed_order_num_.
+
   // Member variables should appear before the WeakPtrFactory, to ensure
   // that any WeakPtrs to Controller are invalidated before its members
   // variable's destructors are executed, rendering them invalid.