Add optimization for CHROMIUM_subscribe_uniform extension.

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 399 matching lines @@
 IPC_MESSAGE_CONTROL1(GpuHostMsg_DidDestroyOffscreenContext,
                      GURL /* url */)
 
 // Tells the browser about GPU memory usage statistics for UMA logging.
 IPC_MESSAGE_CONTROL1(GpuHostMsg_GpuMemoryUmaStats,
                      content::GPUMemoryUmaStats /* GPU memory UMA stats */)
 
 // Response to GpuMsg_RelinquishResources.
 IPC_MESSAGE_CONTROL0(GpuHostMsg_ResourcesRelinquished)
 
+// Tells the browser that a context has subscribed to a new target and
+// the browser should start sending the corresponding information
+IPC_MESSAGE_CONTROL2(GpuHostMsg_AddSubscription,
+                     int32 /* client_id */,
+                     unsigned int /* target */);
+
+// Tells the browser that no contexts are subscribed to the target anymore
+// so the browser should stop sending the corresponding information
+IPC_MESSAGE_CONTROL2(GpuHostMsg_RemoveSubscription,
+                     int32 /* client_id */,
+                     unsigned int /* target */);
+
 //------------------------------------------------------------------------------
 // GPU Channel Messages
 // These are messages from a renderer process to the GPU process.
 
 // Tells the GPU process to create a new command buffer that renders to an
 // offscreen frame buffer.
 IPC_SYNC_MESSAGE_CONTROL3_1(GpuChannelMsg_CreateOffscreenCommandBuffer,
                             gfx::Size, /* size */
                             GPUCreateCommandBufferConfig, /* init_params */
                             int32, /* route_id */
@@ skipping 307 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)