Free context resources when memory limit is 0

content/browser/android/in_process/synchronous_compositor_output_surface.cc

 // Copyright 2013 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 "content/browser/android/in_process/synchronous_compositor_output_surface.h"
 
 #include "base/auto_reset.h"
 #include "base/logging.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/output_surface_client.h"
 #include "cc/output/software_output_device.h"
 #include "content/browser/android/in_process/synchronous_compositor_external_begin_frame_source.h"
 #include "content/browser/android/in_process/synchronous_compositor_impl.h"
 #include "content/browser/android/in_process/synchronous_compositor_registry.h"
 #include "content/browser/gpu/compositor_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/renderer/gpu/frame_swap_message_queue.h"
+#include "gpu/command_buffer/client/context_support.h"
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/common/gpu_memory_allocation.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/skia_util.h"
 #include "ui/gfx/transform.h"
 
 namespace content {
 
 namespace {
@@ skipping 207 matching lines @@
     client_->DidSwapBuffersComplete();
 }
 
 void SynchronousCompositorOutputSurface::ReturnResources(
     const cc::CompositorFrameAck& frame_ack) {
   ReclaimResources(&frame_ack);
 }
 
 void SynchronousCompositorOutputSurface::SetMemoryPolicy(size_t bytes_limit) {
   DCHECK(CalledOnValidThread());
+  bool became_zero = memory_policy_.bytes_limit_when_visible && !bytes_limit;
+  bool became_non_zero =
+      !memory_policy_.bytes_limit_when_visible && bytes_limit;
   memory_policy_.bytes_limit_when_visible = bytes_limit;
   memory_policy_.num_resources_limit = kNumResourcesLimit;
 
   if (client_)
     client_->SetMemoryPolicy(memory_policy_);
+
+  if (became_zero) {
+    // This is small hack to drop context resources without destroying it
+    // when this compositor is put into the background.
+    context_provider()->ContextSupport()->SetSurfaceVisible(false);
+  } else if (became_non_zero) {
+    context_provider()->ContextSupport()->SetSurfaceVisible(true);
+  }
 }
 
 void SynchronousCompositorOutputSurface::SetTreeActivationCallback(
     const base::Closure& callback) {
   DCHECK(client_);
   client_->SetTreeActivationCallback(callback);
 }
 
 void SynchronousCompositorOutputSurface::GetMessagesToDeliver(
     ScopedVector<IPC::Message>* messages) {
   DCHECK(CalledOnValidThread());
   scoped_ptr<FrameSwapMessageQueue::SendMessageScope> send_message_scope =
       frame_swap_message_queue_->AcquireSendMessageScope();
   frame_swap_message_queue_->DrainMessages(messages);
 }
 
 // Not using base::NonThreadSafe as we want to enforce a more exacting threading
 // requirement: SynchronousCompositorOutputSurface() must only be used on the UI
 // thread.
 bool SynchronousCompositorOutputSurface::CalledOnValidThread() const {
   return BrowserThread::CurrentlyOn(BrowserThread::UI);
 }
 
 }  // namespace content