Rework FlushSync to return early if commands have been processed since the last update

gpu/command_buffer/service/gpu_scheduler.cc

 // Copyright (c) 2011 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.
 
 #include "gpu/command_buffer/service/gpu_scheduler.h"
 
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/message_loop.h"
 #include "gpu/common/gpu_trace_event.h"
@@ skipping 99 matching lines @@
 
   parser_.reset();
 }
 
 #if defined(OS_MACOSX)
 namespace {
 const unsigned int kMaxOutstandingSwapBuffersCallsPerOnscreenContext = 1;
 }
 #endif
 
+void GpuScheduler::PutChanged(bool sync) {
+  CommandBuffer::State state = command_buffer_->GetState();
+  parser_->set_put(state.put_offset);
+
+  if (sync)
+    ProcessCommands();
+  else
+    ScheduleProcessCommands();
+}
+
 void GpuScheduler::ProcessCommands() {
   GPU_TRACE_EVENT0("gpu", "GpuScheduler:ProcessCommands");
   CommandBuffer::State state = command_buffer_->GetState();
   if (state.error != error::kNoError)
     return;
 
   if (unscheduled_count_ > 0)
     return;
 
   if (decoder_.get()) {
     if (!decoder_->MakeCurrent()) {
       LOG(ERROR) << "Context lost because MakeCurrent failed.";
       command_buffer_->SetParseError(error::kLostContext);
       return;
     }
   }
 
-  parser_->set_put(state.put_offset);
-
 #if defined(OS_MACOSX)
   bool do_rate_limiting = surface_.get() != NULL;
   // Don't swamp the browser process with SwapBuffers calls it can't handle.
   if (do_rate_limiting &&
       swap_buffers_count_ - acknowledged_swap_buffers_count_ >=
       kMaxOutstandingSwapBuffersCallsPerOnscreenContext) {
     // Stop doing work on this command buffer. In the GPU process,
     // receipt of the GpuMsg_AcceleratedSurfaceBuffersSwappedACK
     // message causes ProcessCommands to be scheduled again.
     return;
@@ skipping 84 matching lines @@
   command_processed_callback_.reset(callback);
 }
 
 void GpuScheduler::ScheduleProcessCommands() {
   MessageLoop::current()->PostTask(
       FROM_HERE,
       method_factory_.NewRunnableMethod(&GpuScheduler::ProcessCommands));
 }
 
 }  // namespace gpu