Mac: Don't hang gpu process on popup close under certain conditions

gpu/command_buffer/service/gpu_processor_mac.cc

 // Copyright (c) 2010 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 "app/gfx/gl/gl_context.h"
 #include "gpu/command_buffer/service/gpu_processor.h"
 
 using ::base::SharedMemory;
 
 namespace gpu {
@@ skipping 90 matching lines @@
 
 uint64 GPUProcessor::swap_buffers_count() const {
   return swap_buffers_count_;
 }
 
 void GPUProcessor::set_acknowledged_swap_buffers_count(
     uint64 acknowledged_swap_buffers_count) {
   acknowledged_swap_buffers_count_ = acknowledged_swap_buffers_count;
 }
 
+void GPUProcessor::DidDestroySurface() {
+  // When a browser window with a GPUProcessor is closed, the render process
+  // will attempt to finish all GL commands, it will busy-wait on the GPU
+  // process until the command queue is empty. If a paint is pending, the GPU
+  // process won't process any GL commands until the browser sends a paint ack,
+  // but since the browser window is already closed, it will never arrive.
+  // To break this infinite loop, the browser tells the GPU process that the
+  // surface became invalid, which causes the GPU process to not wait for paint
+  // acks.
+  surface_.reset();
+}
+
 void GPUProcessor::WillSwapBuffers() {
   DCHECK(decoder_.get());
   DCHECK(decoder_->GetGLContext());
   DCHECK(decoder_->GetGLContext()->IsCurrent());
 
   ++swap_buffers_count_;
 
   if (surface_.get()) {
     surface_->SwapBuffers();
   }
 
   if (wrapped_swap_buffers_callback_.get()) {
     wrapped_swap_buffers_callback_->Run();
   }
 }
 
 }  // namespace gpu