Frames received after guest detaches should be displayed.

content/browser/frame_host/render_widget_host_view_guest.cc

 // Copyright 2014 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/frame_host/render_widget_host_view_guest.h"
 
 #include <utility>
 
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
@@ skipping 189 matching lines @@
 
 void RenderWidgetHostViewGuest::SetTooltipText(
     const base::string16& tooltip_text) {
   if (guest_)
     guest_->SetTooltipText(tooltip_text);
 }
 
 void RenderWidgetHostViewGuest::OnSwapCompositorFrame(
     uint32_t output_surface_id,
     scoped_ptr<cc::CompositorFrame> frame) {
-  if (!guest_ || !guest_->attached()) {
-    // We shouldn't hang on to a surface while we are detached.
-    ClearCompositorSurfaceIfNecessary();
-    return;
-  }
+  // If after detaching we are sent a frame, we should finish processing it, and
+  // then we should clear the surface so that we are not holding resources we
+  // no longer need.
+  bool should_clear_compositor_surface_on_exit = !guest_ || !guest_->attached();

[wjmaclean, 2016/03/08 16:13:06]

We don't actually need to declare a var for this if we don't want to, rather we
can just check !guest_ || !guest_->attached() in the if-statement at the end.

 
   last_scroll_offset_ = frame->metadata.root_scroll_offset;
 
   cc::RenderPass* root_pass =
       frame->delegated_frame_data->render_pass_list.back().get();
 
   gfx::Size frame_size = root_pass->output_rect.size();
   float scale_factor = frame->metadata.device_scale_factor;
 
   // Check whether we need to recreate the cc::Surface, which means the child
@@ skipping 34 matching lines @@
   cc::SurfaceFactory::DrawCallback ack_callback = base::Bind(
       &RenderWidgetHostViewChildFrame::SurfaceDrawn,
       RenderWidgetHostViewChildFrame::AsWeakPtr(), output_surface_id);
   ack_pending_count_++;
   // If this value grows very large, something is going wrong.
   DCHECK(ack_pending_count_ < 1000);
   surface_factory_->SubmitCompositorFrame(surface_id_, std::move(frame),
                                           ack_callback);
 
   ProcessFrameSwappedCallbacks();
+
+  if (should_clear_compositor_surface_on_exit)
+    ClearCompositorSurfaceIfNecessary();
 }
 
 bool RenderWidgetHostViewGuest::OnMessageReceived(const IPC::Message& msg) {
   if (!platform_view_) {
     // In theory, we can get here if there's a delay between DestroyGuestView()
     // being called and when our destructor is invoked.
     return false;
   }
 
   return platform_view_->OnMessageReceived(msg);
@@ skipping 349 matching lines @@
     if (gesture_event.type == blink::WebInputEvent::GestureScrollUpdate &&
         gesture_event.data.scrollUpdate.inertial) {
       return;
     }
     host_->ForwardGestureEvent(gesture_event);
     return;
   }
 }
 
 }  // namespace content