cc: Throttle swaps in Scheduler instead of OutputSurface

cc/test/fake_output_surface.cc

 // Copyright 2012 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 "cc/test/fake_output_surface.h"
 
 #include "base/bind.h"
 #include "base/message_loop/message_loop.h"
 #include "cc/output/compositor_frame_ack.h"
 #include "cc/output/output_surface_client.h"
@@ skipping 45 matching lines @@
       fake_weak_ptr_factory_(this) {
   if (delegated_rendering) {
     capabilities_.delegated_rendering = true;
     capabilities_.max_frames_pending = 1;
   }
 }
 
 FakeOutputSurface::~FakeOutputSurface() {}
 
 void FakeOutputSurface::SwapBuffers(CompositorFrame* frame) {
+  // In unit tests we sometimes lose the context synchronously during a draw,
+  // so we abort the swap here if that's the case. Real implementations of
+  // OutputSurface should DCHECK that is_lost_ is false.
+  if (is_lost_)

[brianderson, 2014/04/12 00:09:58]

I decided to DCHECK for all other OutputSurface implementations.

[danakj, 2014/04/14 18:14:51]

Hm, there's no point in a unit test that can't happen in reality. We should
understand why these tests can't actually happen and remove them/change them to
match reality.

In single thread, right now we check for lost context after drawing, and return
false from DoComposite() to avoid swapping.

We could check in the ThreadProxy to get similar behaviour. Right now I don't
think we do, so we could lose the context during draw but do the swap hitting
the DCHECK?

But why do we care if we SwapBuffers on a lost surface anyway?

[brianderson, 2014/04/16 22:41:53]

I'm going to remove the is_lost_ checks.

+    return;
+
   if (frame->software_frame_data || frame->delegated_frame_data ||
       !context_provider()) {
     frame->AssignTo(&last_sent_frame_);
 
     if (last_sent_frame_.delegated_frame_data) {
       resources_held_by_parent_.insert(
           resources_held_by_parent_.end(),
           last_sent_frame_.delegated_frame_data->resource_list.begin(),
           last_sent_frame_.delegated_frame_data->resource_list.end());
     }
@@ skipping 67 matching lines @@
 bool FakeOutputSurface::HasExternalStencilTest() const {
   return has_external_stencil_test_;
 }
 
 void FakeOutputSurface::SetMemoryPolicyToSetAtBind(
     scoped_ptr<ManagedMemoryPolicy> memory_policy_to_set_at_bind) {
   memory_policy_to_set_at_bind_.swap(memory_policy_to_set_at_bind);
 }
 
 }  // namespace cc