(not for commit) Simplified multi-threaded Ganesh with lock on Flush only.

gpu/command_buffer/client/gles2_implementation.cc

Index: gpu/command_buffer/client/gles2_implementation.cc
diff --git a/gpu/command_buffer/client/gles2_implementation.cc b/gpu/command_buffer/client/gles2_implementation.cc
index b4628a0b0735a2810c760d9044a84b2f0bb8768b..1d4de5ad25a533939e3f0c289fd55e9d588e9ece 100644
--- a/gpu/command_buffer/client/gles2_implementation.cc
+++ b/gpu/command_buffer/client/gles2_implementation.cc
@@ -833,6 +833,19 @@ void GLES2Implementation::ShallowFlushCHROMIUM() {
   // TODO(piman): Add the FreeEverything() logic here.
 }
 
+void GLES2Implementation::SetSafeFlushPoint() {
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glSetSafeFlushPoint()");
+  // Save the current command offset for SafeFlush().
+  helper_->CommandBufferHelper::SetSafeFlushPoint();
+}
+
+void GLES2Implementation::SafeFlush() {
+  GPU_CLIENT_LOG("[" << GetLogPrefix() << "] glSafeFlushCHROMIUM()");
+  // Flush our command buffer up to the last safe flush point.
+  // (tell the service to execute up to the flush cmd.)
+  helper_->CommandBufferHelper::SafeFlush();
+}
+
 void GLES2Implementation::Finish() {
   GPU_CLIENT_SINGLE_THREAD_CHECK();
   FinishHelper();