Added method to synchronize command buffers within GpuControl.

content/common/gpu/client/command_buffer_proxy_impl.cc

Index: content/common/gpu/client/command_buffer_proxy_impl.cc
diff --git a/content/common/gpu/client/command_buffer_proxy_impl.cc b/content/common/gpu/client/command_buffer_proxy_impl.cc
index 1a604959312899cb42c0fc5e52b12531125444f1..a8b4ba0fe0b34abb87d65a56fecf28e532600773 100644
--- a/content/common/gpu/client/command_buffer_proxy_impl.cc
+++ b/content/common/gpu/client/command_buffer_proxy_impl.cc
@@ -455,7 +455,7 @@ int32_t CommandBufferProxyImpl::CreateImage(ClientBuffer buffer,
                               GetCommandBufferID(), image_fence_sync);
 
     // Force a synchronous IPC to validate sync token.
-    channel_->ValidateFlushIDReachedServer(stream_id_, true);
+    EnsureWorkVisible();
     sync_token.SetVerifyFlush();
 
     gpu_memory_buffer_manager->SetDestructionSyncToken(gpu_memory_buffer,
@@ -514,6 +514,10 @@ bool CommandBufferProxyImpl::IsGpuChannelLost() {
   return !channel_ || channel_->IsLost();
 }
 
+void CommandBufferProxyImpl::EnsureWorkVisible() {
+  channel_->ValidateFlushIDReachedServer(stream_id_, true);
+}
+
 gpu::CommandBufferNamespace CommandBufferProxyImpl::GetNamespaceID() const {
   return gpu::CommandBufferNamespace::GPU_IO;
 }