Discard compositor frames from unloaded web content

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 <memory>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 359 matching lines @@
       resizing_mode_selector_(new ResizingModeSelector()),
       has_host_context_menu_location_(false),
       has_added_input_handler_(false),
       has_focus_(false),
 #if defined(OS_MACOSX)
       text_input_client_observer_(new TextInputClientObserver(this)),
 #endif
       focused_pepper_plugin_(nullptr),
       time_to_first_active_paint_recorded_(true),
       was_shown_time_(base::TimeTicks::Now()),
+      current_content_source_id_(0),
       weak_ptr_factory_(this) {
   DCHECK_NE(routing_id_, MSG_ROUTING_NONE);
   if (!swapped_out)
     RenderProcess::current()->AddRefProcess();
   DCHECK(RenderThread::Get());
 
   // In tests there may not be a RenderThreadImpl.
   if (RenderThreadImpl::current()) {
     render_widget_scheduling_state_ = RenderThreadImpl::current()
                                           ->GetRendererScheduler()
@@ skipping 887 matching lines @@
   auto layer_tree_host = RenderWidgetCompositor::CreateLayerTreeHost(
       compositor_.get(), compositor_.get(), animation_host.get(),
       compositor_deps_, device_scale_factor_, screen_info_);
   compositor_->Initialize(std::move(layer_tree_host),
                           std::move(animation_host));
 
   compositor_->SetIsForOopif(for_oopif_);
   compositor_->setViewportSize(physical_backing_size_);
   OnDeviceScaleFactorChanged();
   compositor_->SetDeviceColorSpace(screen_info_.icc_profile.GetColorSpace());
+  compositor_->SetContentSourceId(current_content_source_id_);
   // For background pages and certain tests, we don't want to trigger
   // CompositorFrameSink creation.
   if (compositor_never_visible_ || !RenderThreadImpl::current())
     compositor_->SetNeverVisible();
 
   StartCompositor();
   DCHECK_NE(MSG_ROUTING_NONE, routing_id_);
   compositor_->SetFrameSinkId(
       cc::FrameSinkId(RenderThread::Get()->GetClientId(), routing_id_));
 
@@ skipping 994 matching lines @@
   blink::WebRect offset_in_window(webImageOffset.x, webImageOffset.y, 0, 0);
   convertViewportToWindow(&offset_in_window);
   DropData drop_data(DropDataBuilder::Build(data));
   drop_data.referrer_policy = policy;
   gfx::Vector2d imageOffset(offset_in_window.x, offset_in_window.y);
   Send(new DragHostMsg_StartDragging(routing_id(), drop_data, mask,
                                      image.getSkBitmap(), imageOffset,
                                      possible_drag_event_info_));
 }
 
+uint32_t RenderWidget::GetContentSourceId() {
+  return current_content_source_id_;
+}
+
+void RenderWidget::IncrementContentSourceId() {
+  if (compositor_)
+    compositor_->SetContentSourceId(++current_content_source_id_);
+}
+
 blink::WebWidget* RenderWidget::GetWebWidget() const {
   return webwidget_internal_;
 }
 
 blink::WebInputMethodController* RenderWidget::GetInputMethodController()
     const {
   if (!GetWebWidget()->isWebFrameWidget()) {
     // TODO(ekaramad): We should not get here in response to IME IPC or updates
     // when the RenderWidget is swapped out. We should top sending IPCs from the
     // browser side (https://crbug.com/669219).
     // If there is no WebFrameWidget, then there will be no
     // InputMethodControllers for a WebLocalFrame.
     return nullptr;
   }
   return static_cast<blink::WebFrameWidget*>(GetWebWidget())
       ->getActiveWebInputMethodController();
 }
 
 }  // namespace content