Rebind EGL context to flush driver caches.

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"
@@ skipping 240 matching lines @@
   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()->SetAggressivelyFreeResources(
         true /* aggressively_free_resources */);
+    context_provider()->ContextGL()->FlushDriverCachesCHROMIUM();

[piman, 2015/07/13 21:25:29]

Should we do this before SetAggressivelyFreeResources?
Otherwise:
- SetAggressivelyFreeResources finished, and freed the command buffer
- FlushDriverCachesCHROMIUM reallocates the command buffer to put the command
in, and doesn't flush - so it won't actually happen until the next Flush, and we
still hold on to the command buffer memory in the mean time.

Either that or it could even be done inside of SetAggressivelyFreeResources.


Separately, don't we want to do this also for the !webview case, i.e. the other
places we call SetAggressivelyFreeResources?

[ericrk, 2015/07/13 22:11:11]

Moved this to FreeEverything.

   } else if (became_non_zero) {
     context_provider()->ContextSupport()->SetAggressivelyFreeResources(
         false /* aggressively_free_resources */);
   }
 }
 
 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