Added method to synchronize command buffers within GpuControl.

gpu/command_buffer/service/in_process_command_buffer.cc

Index: gpu/command_buffer/service/in_process_command_buffer.cc
diff --git a/gpu/command_buffer/service/in_process_command_buffer.cc b/gpu/command_buffer/service/in_process_command_buffer.cc
index ef3097facd6a703cd9a0c364a9e27c030b034b63..ddcca38bac78b9138965b53bc001683124ae98ce 100644
--- a/gpu/command_buffer/service/in_process_command_buffer.cc
+++ b/gpu/command_buffer/service/in_process_command_buffer.cc
@@ -984,6 +984,10 @@ bool InProcessCommandBuffer::IsGpuChannelLost() {
   return false;
 }
 
+void InProcessCommandBuffer::SynchronizeCommandBuffer() {
+  // This is only relevant for out-of-process command buffers.
+}
+
 CommandBufferNamespace InProcessCommandBuffer::GetNamespaceID() const {
   return CommandBufferNamespace::IN_PROCESS;
 }