Fixes failing instrumentation tests on Nakasi

content/browser/renderer_host/render_widget_host_view_android.cc

 // Copyright (c) 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 "content/browser/renderer_host/render_widget_host_view_android.h"
 
 #include <android/bitmap.h>
 #include <utility>
 
 #include "base/android/build_info.h"
@@ skipping 535 matching lines @@
 
 void RenderWidgetHostViewAndroid::LockCompositingSurface() {
   DCHECK(HasValidFrame());
   DCHECK(host_);
   DCHECK(frame_evictor_->HasFrame());
   frame_evictor_->LockFrame();
   locks_on_frame_count_++;
 }
 
 void RenderWidgetHostViewAndroid::UnlockCompositingSurface() {
-  if (!frame_evictor_->HasFrame() || locks_on_frame_count_ == 0)
+  if (!frame_evictor_->HasFrame() || locks_on_frame_count_ == 0 ||
+      !layer_.get())

[no sievers, 2016/03/18 00:42:15]

I'm worried that this can mess up our |locks_on_frame_count_| and we end up
creating a new |layer_| and the lock count is now nonzero. It's also weird that
there is an early-out here for 'locks_on_frame_count_ == 0' which explicitly
seems to allow unbalanced calls.

Is the problem maybe this sequence?
void RenderWidgetHostViewAndroid::Destroy() {
  RemoveLayers();
  SetContentViewCore(NULL); -> can call ReleaseLocksOnSurface()

Note that there is another call to RemoveLayers() at the top of
SetContentViewCore().

It think it makes sense to ensure that we release locks on the 'compositing
surface' (which really is the layer) before we delete the layer.

[Jinsuk Kim, 2016/03/21 04:52:35]

locks_on_frame_count_ == 0 can be removed and replaced with DCHECK_EQ as done in
ReleaseLocksOnSurface(). For that, called frame_evictor_->DiscardedFrame()
before DestroyDelegatedContent() (please see  EvictDelegatedFrame()) to have
frame_evictor_->HasFrame() return false.

     return;
 
   DCHECK(HasValidFrame());
   frame_evictor_->UnlockFrame();
   locks_on_frame_count_--;
 
   if (locks_on_frame_count_ == 0) {
     if (last_frame_info_) {
       InternalSwapCompositorFrame(last_frame_info_->output_surface_id,
                                   std::move(last_frame_info_->frame));
@@ skipping 232 matching lines @@
 void RenderWidgetHostViewAndroid::FocusedNodeChanged(bool is_editable_node) {
   ime_adapter_android_.FocusedNodeChanged(is_editable_node);
 }
 
 void RenderWidgetHostViewAndroid::RenderProcessGone(
     base::TerminationStatus status, int error_code) {
   Destroy();
 }
 
 void RenderWidgetHostViewAndroid::Destroy() {
+  host_->ViewDestroyed();
   RemoveLayers();
   SetContentViewCore(NULL);
 
   if (!surface_id_.is_null()) {
     DCHECK(surface_factory_.get());
     surface_factory_->Destroy(surface_id_);
     surface_id_ = cc::SurfaceId();
   }
   surface_factory_.reset();
 
@@ skipping 1200 matching lines @@
   results->orientationAngle = display.RotationAsDegree();
   results->orientationType =
       RenderWidgetHostViewBase::GetOrientationTypeForMobile(display);
   gfx::DeviceDisplayInfo info;
   results->depth = info.GetBitsPerPixel();
   results->depthPerComponent = info.GetBitsPerComponent();
   results->isMonochrome = (results->depthPerComponent == 0);
 }
 
 }  // namespace content