GPU: Adding sync points for cross-channel synchronization

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 440 matching lines @@
 
 // Sent to proxy when the gpu memory manager changes its memory allocation.
 IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_SetMemoryAllocation,
                     GpuMemoryAllocationForRenderer /* allocation */)
 
 // Sent to stub when proxy is assigned a memory allocation changed callback.
 IPC_MESSAGE_ROUTED1(
     GpuCommandBufferMsg_SetClientHasMemoryAllocationChangedCallback,
     bool /* has_callback */)
 
+// Inserts a sync point into the channel. This is handled on the IO thread, so
+// can be expected to be reasonably fast, but the sync point is actually
+// retired in order with respect to the other calls. The sync point is shared
+// across channels.
+IPC_SYNC_MESSAGE_ROUTED0_1(GpuCommandBufferMsg_InsertSyncPoint,
+                           uint32 /* sync_point */)
+
+// Retires the sync point. Note: this message is not sent explicitly by the
+// renderer, but is synthesized by the GPU process.
+IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_RetireSyncPoint,
+                    uint32 /* sync_point */)
+
+// Makes this command buffer wait on a sync point. Command buffer message
+// execution will be delayed until the sync point has been reached.
+IPC_MESSAGE_ROUTED1(GpuCommandBufferMsg_WaitSyncPoint,
+                    uint32 /* sync_point */)
+
 //------------------------------------------------------------------------------
 // Accelerated Video Decoder Messages
 // These messages are sent from Renderer process to GPU process.
 
 // Send input buffer for decoding.
 IPC_MESSAGE_ROUTED3(AcceleratedVideoDecoderMsg_Decode,
                     base::SharedMemoryHandle, /* input_buffer_handle */
                     int32, /* bitstream_buffer_id */
                     int32) /* size */
 
@@ skipping 45 matching lines @@
 
 // Confirm decoder has been flushed.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_FlushDone)
 
 // Confirm decoder has been reset.
 IPC_MESSAGE_ROUTED0(AcceleratedVideoDecoderHostMsg_ResetDone)
 
 // Video decoder has encountered an error.
 IPC_MESSAGE_ROUTED1(AcceleratedVideoDecoderHostMsg_ErrorNotification,
                     uint32) /* Error ID */