Fix race between DPI and window size

content/browser/renderer_host/render_widget_host_impl.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_impl.h"
 
 #include <math.h>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 129 matching lines @@
       delegate_(delegate),
       process_(process),
       routing_id_(routing_id),
       surface_id_(0),
       is_loading_(false),
       is_hidden_(false),
       is_fullscreen_(false),
       is_accelerated_compositing_active_(false),
       repaint_ack_pending_(false),
       resize_ack_pending_(false),
+      renderer_screen_info_out_of_date_(false),
       overdraw_bottom_height_(0.f),
       should_auto_resize_(false),
       waiting_for_screen_rects_ack_(false),
       mouse_move_pending_(false),
       mouse_wheel_pending_(false),
       accessibility_mode_(AccessibilityModeOff),
       select_range_pending_(false),
       move_caret_pending_(false),
       needs_repainting_on_restore_(false),
       is_unresponsive_(false),
@@ skipping 359 matching lines @@
 
   gfx::Size old_physical_backing_size = physical_backing_size_;
   physical_backing_size_ = view_->GetPhysicalBackingSize();
   bool was_fullscreen = is_fullscreen_;
   is_fullscreen_ = IsFullscreen();
   float old_overdraw_bottom_height = overdraw_bottom_height_;
   overdraw_bottom_height_ = view_->GetOverdrawBottomHeight();
 
   bool size_changed = new_size != current_size_;
   bool side_payload_changed =
+      renderer_screen_info_out_of_date_ ||
       old_physical_backing_size != physical_backing_size_ ||
       was_fullscreen != is_fullscreen_ ||
       old_overdraw_bottom_height != overdraw_bottom_height_;
 
   if (!size_changed && !side_payload_changed)
     return;
 
   if (in_flight_size_ != gfx::Size() && new_size == in_flight_size_ &&
       !side_payload_changed)
     return;
 
   // We don't expect to receive an ACK when the requested size or the physical
   // backing size is empty, or when the main viewport size didn't change.
   if (!new_size.IsEmpty() && !physical_backing_size_.IsEmpty() && size_changed)
     resize_ack_pending_ = true;
 
-  if (!Send(new ViewMsg_Resize(routing_id_, new_size, physical_backing_size_,
-                               overdraw_bottom_height_,
-                               GetRootWindowResizerRect(), is_fullscreen_))) {
+  ViewMsg_Resize_Params params;
+  GetWebScreenInfo(&params.screen_info);

[piman, 2013/05/25 00:37:25]

This could be a bit expensive, like round-tripping to X on linux, but done on
every resize. Could we still query it in NotifyScreenInfoChanged which should
only happen rarely, and cache it as a field?

[ccameron, 2013/05/25 01:53:37]

Yes, I was on the fence about this. I didn't initially put it in because of the
include order issue. I've updated this to have a scoped_ptr<> which is reset
when it becomes invalid.

+  params.new_size = new_size;
+  params.physical_backing_size = physical_backing_size_;
+  params.overdraw_bottom_height = overdraw_bottom_height_;
+  params.resizer_rect = GetRootWindowResizerRect();
+  params.is_fullscreen = is_fullscreen_;
+  if (!Send(new ViewMsg_Resize(routing_id_, params))) {
     resize_ack_pending_ = false;
   } else {
     in_flight_size_ = new_size;
+    renderer_screen_info_out_of_date_ = false;
   }
 }
 
 void RenderWidgetHostImpl::ResizeRectChanged(const gfx::Rect& new_rect) {
   Send(new ViewMsg_ChangeResizeRect(routing_id_, new_rect));
 }
 
 void RenderWidgetHostImpl::GotFocus() {
   Focus();
 }
@@ skipping 765 matching lines @@
 }
 
 const NativeWebKeyboardEvent*
     RenderWidgetHostImpl::GetLastKeyboardEvent() const {
   if (key_queue_.empty())
     return NULL;
   return &key_queue_.front();
 }
 
 void RenderWidgetHostImpl::NotifyScreenInfoChanged() {
-  WebKit::WebScreenInfo screen_info;
-  GetWebScreenInfo(&screen_info);
-  Send(new ViewMsg_ScreenInfoChanged(GetRoutingID(), screen_info));
+  // The resize message (which may not happen immediately) will carry with it
+  // the screen info as well as the new size (if the screen has changed scale
+  // factor).
+  renderer_screen_info_out_of_date_ = true;
+  WasResized();
 }
 
 void RenderWidgetHostImpl::GetSnapshotFromRenderer(
     const gfx::Rect& src_subrect,
     const base::Callback<void(bool, const SkBitmap&)>& callback) {
   TRACE_EVENT0("browser", "RenderWidgetHostImpl::GetSnapshotFromRenderer");
   pending_snapshots_.push(callback);
 
   gfx::Rect copy_rect = src_subrect.IsEmpty() ?
       gfx::Rect(view_->GetViewBounds().size()) : src_subrect;
@@ skipping 1127 matching lines @@
 }
 
 void RenderWidgetHostImpl::DetachDelegate() {
   delegate_ = NULL;
 }
 
 void RenderWidgetHostImpl::FrameSwapped(const cc::LatencyInfo& latency_info) {
 }
 
 }  // namespace content