gpu: Remove Echo and SwapCompletion GL interfacess

content/common/gpu/gpu_channel.h

Index: content/common/gpu/gpu_channel.h
diff --git a/content/common/gpu/gpu_channel.h b/content/common/gpu/gpu_channel.h
index e48eaa1edfb99ad257aca7b18e4a9d36c048ff7b..06f08129941f555009f780783dd7b691349c029e 100644
--- a/content/common/gpu/gpu_channel.h
+++ b/content/common/gpu/gpu_channel.h
@@ -167,11 +167,8 @@ class GpuChannel : public IPC::Listener, public IPC::Sender {
   // Decrement the count of unhandled IPC messages and defer preemption.
   void MessageProcessed();
 
-  // Try to match the messages pattern for GL SwapBuffers operation in the
-  // deferred message queue starting from the current processing message.
-  // Return the number of messages that matches the given pattern, e.g.
-  // AsyncFlush -> Echo sequence.
-  size_t MatchSwapBufferMessagesPattern(IPC::Message* current_message);
+  // Checks if there is a RetireSyncPoint following a Flush.
+  size_t MatchRetireSyncPointPattern(IPC::Message* current_message);
 
   // The lifetime of objects of this class is managed by a GpuChannelManager.
   // The GpuChannelManager destroy all the GpuChannels that they own when they