gpu: Remove Echo and SwapCompletion GL interfacess

content/common/gpu/gpu_messages.h

 // Copyright (c) 2012 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.
 
 // Multiply-included message file, hence no include guard here, but see below
 // for a much smaller-than-usual include guard section.
 
 #include <string>
 #include <vector>
 
@@ skipping 522 matching lines @@
                            media::VideoCodecProfile /* output_profile */,
                            uint32 /* initial_bitrate */,
                            int32, /* route_id */
                            bool /* succeeded */)
 
 // Tells the proxy that there was an error and the command buffer had to be
 // destroyed for some reason.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_Destroyed,
                     gpu::error::ContextLostReason /* reason */)
 
-// Request that the GPU process reply with the given message. Reply may be
-// delayed.
-IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_Echo,
-                    IPC::Message /* reply */)
-
-// Response to a GpuChannelMsg_Echo message.
-IPC_MESSAGE_ROUTED0(GpuCommandBufferMsg_EchoAck)
-
 // Send to stub on surface visibility change.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_SetSurfaceVisible, bool /* visible */)
 
 // Sent to proxy when the gpu memory manager changes its memory allocation.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_SetMemoryAllocation,
                     gpu::MemoryAllocation /* allocation */)
 
 // Sent to stub when proxy is assigned a memory allocation changed callback.
 IPC_MESSAGE_ROUTED1(
     GpuCommandBufferMsg_SetClientHasMemoryAllocationChangedCallback,
@@ skipping 163 matching lines @@
                     int32 /* bitstream_buffer_id */,
                     uint32 /* payload_size */,
                     bool /* key_frame */)
 
 // Report error condition.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoEncoderHostMsg_NotifyError,
                     media::VideoEncodeAccelerator::Error /* error */)
 
 // Send destroy request to the encoder.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoEncoderMsg_Destroy)