Make SingleThreadProxy a SchedulerClient

content/renderer/render_widget.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/renderer/render_widget.h"
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 375 matching lines @@
       did_show_(false),
       is_hidden_(hidden),
       never_visible_(never_visible),
       is_fullscreen_(false),
       has_focus_(false),
       handling_input_event_(false),
       handling_ime_event_(false),
       handling_event_type_(WebInputEvent::Undefined),
       ignore_ack_for_mouse_move_from_debugger_(false),
       closing_(false),
+      host_closing_(false),

[danakj, 2014/08/13 18:30:19]

This var could exist #if DCHECK_IS_ON

       is_swapped_out_(swapped_out),
       input_method_is_active_(false),
       text_input_type_(ui::TEXT_INPUT_TYPE_NONE),
       text_input_mode_(ui::TEXT_INPUT_MODE_DEFAULT),
       can_compose_inline_(true),
       popup_type_(popup_type),
       pending_window_rect_count_(0),
       suppress_next_char_events_(false),
       screen_info_(screen_info),
       device_scale_factor_(screen_info_.deviceScaleFactor),
@@ skipping 788 matching lines @@
 }
 
 void RenderWidget::AutoResizeCompositor()  {
   physical_backing_size_ = gfx::ToCeiledSize(gfx::ScaleSize(size_,
       device_scale_factor_));
   if (compositor_)
     compositor_->setViewportSize(size_, physical_backing_size_);
 }
 
 void RenderWidget::initializeLayerTreeView() {
+  DCHECK(!host_closing_);
+
   compositor_ =
       RenderWidgetCompositor::Create(this, IsThreadedCompositingEnabled());
   compositor_->setViewportSize(size_, physical_backing_size_);
   if (init_complete_)
     StartCompositor();
 }
 
+void RenderWidget::DestroyLayerTreeView() {
+  // Always send this notification to prevent new layer tree views from
+  // being created, even if one hasn't been created yet.
+  webwidget_->willCloseLayerTreeView();

[danakj, 2014/08/13 18:30:19]

Ok so my super deep (ha ha haahha) understanding of this is that JS can request
a WebWidget to close by calling closeWidgetSoon on it's client (here). Then
we'll post a DoDeferredClose which will call this method.

But at the same time the user might close the window from the UI, shutting down
the RenderViewHostImpl, which will end up in RVHI::Shutdown->RWHI::Shutdown
which sends Close to the RenderWidget. Then DestroyLayerTreeView can't call
willCloseLayerTreeView cuz webwidget_ has been closed and destroyed already. So
you need to check this variable for null.

+  compositor_.reset();
+}
+
 blink::WebLayerTreeView* RenderWidget::layerTreeView() {
   return compositor_.get();
 }
 
-void RenderWidget::suppressCompositorScheduling(bool enable) {
-  if (compositor_)
-    compositor_->SetSuppressScheduleComposite(enable);
-}
-
 void RenderWidget::willBeginCompositorFrame() {
   TRACE_EVENT0("gpu", "RenderWidget::willBeginCompositorFrame");
 
-  DCHECK(RenderThreadImpl::current()->compositor_message_loop_proxy().get());
-
   // The following two can result in further layout and possibly
   // enable GPU acceleration so they need to be called before any painting
   // is done.
   UpdateTextInputState(NO_SHOW_IME, FROM_NON_IME);
   UpdateSelectionBounds();
 }
 
 void RenderWidget::didBecomeReadyForAdditionalInput() {
   TRACE_EVENT0("renderer", "RenderWidget::didBecomeReadyForAdditionalInput");
   FlushPendingInputEventAck();
@@ skipping 136 matching lines @@
   SetPendingWindowRect(initial_pos_);
 }
 
 void RenderWidget::didFocus() {
 }
 
 void RenderWidget::didBlur() {
 }
 
 void RenderWidget::DoDeferredClose() {
+  // No more compositing is possible.  This prevents shutdown races between
+  // previously posted CreateOutputSurface tasks and the host being unable to
+  // create them because the close message was handled.
+  DestroyLayerTreeView();
+  // Also prevent new compositors from being created.
+  host_closing_ = true;
   Send(new ViewHostMsg_Close(routing_id_));
 }
 
 void RenderWidget::closeWidgetSoon() {
   if (is_swapped_out_) {
     // This widget is currently swapped out, and the active widget is in a
     // different process.  Have the browser route the close request to the
     // active widget instead, so that the correct unload handlers are run.
     Send(new ViewHostMsg_RouteCloseEvent(routing_id_));
     return;
@@ skipping 20 matching lines @@
 
   SyntheticGesturePacket gesture_packet;
   gesture_packet.set_gesture_params(gesture_params.Pass());
 
   Send(new InputHostMsg_QueueSyntheticGesture(routing_id_, gesture_packet));
 }
 
 void RenderWidget::Close() {
   screen_metrics_emulator_.reset();
   if (webwidget_) {
-    webwidget_->willCloseLayerTreeView();
-    compositor_.reset();
+    DestroyLayerTreeView();
     webwidget_->close();
     webwidget_ = NULL;
   }
 }
 
 WebRect RenderWidget::windowRect() {
   if (pending_window_rect_count_)
     return pending_window_rect_;
 
   return view_screen_rect_;
@@ skipping 723 matching lines @@
 void RenderWidget::RegisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.AddObserver(frame);
 }
 
 void RenderWidget::UnregisterVideoHoleFrame(RenderFrameImpl* frame) {
   video_hole_frames_.RemoveObserver(frame);
 }
 #endif  // defined(VIDEO_HOLE)
 
 }  // namespace content