Make WebWidget::resize early out if the size doesn't change.

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 670 matching lines @@
     std::unique_ptr<cc::SwapPromiseMonitor> latency_info_swap_promise_monitor(
         compositor_->CreateLatencyInfoSwapPromiseMonitor(&swap_latency_info));
     compositor_->SetNeedsForcedRedraw();
   }
   ScheduleComposite();
 }
 
 void RenderWidget::OnRequestMoveAck() {
   DCHECK(pending_window_rect_count_);
   pending_window_rect_count_--;
+  if (!pending_window_rect_count_)
+    view_screen_rect_ = pending_window_rect_;

[bokan, 2016/04/21 22:04:44]

In making the changes to WebPagePopupImpl, I noticed that when we setWindowRect,
we set pending_window_rect_ to the given rect. Then in windowRect we return the
pending_window_rect_ until we get back a MoveAck and thereafter we return the
view_screen_rect_. However, we never actually update the view_screen_rect_!

This code is quite long lived (last touched by Darin, in fact) so I'm surprised
to have found such a glaring bug, perhaps I just don't understand the whole
picture. Are you familiar with this code or know someone who is? Maybe it's just
used for popups, and the popup kept it's own copy of the rect until now so it
didn't come up as a problem...

 }
 
 GURL RenderWidget::GetURLForGraphicsContext3D() {
   return GURL();
 }
 
 void RenderWidget::OnHandleInputEvent(const blink::WebInputEvent* input_event,
                                       const ui::LatencyInfo& latency_info,
                                       InputEventDispatchType dispatch_type) {
   if (!input_event)
@@ skipping 441 matching lines @@
     DCHECK(!params.needs_resize_ack || !next_paint_is_resize_ack());
   }
 
   // Ignore this during shutdown.
   if (!webwidget_)
     return;
 
   if (compositor_)
     compositor_->setViewportSize(params.physical_backing_size);
 
-  bool resized = size_ != params.new_size ||
-                 physical_backing_size_ != params.physical_backing_size;
-
   size_ = params.new_size;
   physical_backing_size_ = params.physical_backing_size;
 
   top_controls_shrink_blink_size_ = params.top_controls_shrink_blink_size;
   top_controls_height_ = params.top_controls_height;
   visible_viewport_size_ = params.visible_viewport_size;
   resizer_rect_ = params.resizer_rect;
 
   // NOTE: We may have entered fullscreen mode without changing our size.
   bool fullscreen_change =
       is_fullscreen_granted_ != params.is_fullscreen_granted;
   is_fullscreen_granted_ = params.is_fullscreen_granted;
   display_mode_ = params.display_mode;
 
   webwidget_->setTopControlsHeight(params.top_controls_height,
                                    top_controls_shrink_blink_size_);
 
-  if (resized) {
-    gfx::Size new_widget_size = size_;
-    if (IsUseZoomForDSFEnabled()) {
-      new_widget_size = gfx::ScaleToCeiledSize(new_widget_size,
-                                               GetOriginalDeviceScaleFactor());
-    }
-    // When resizing, we want to wait to paint before ACK'ing the resize.  This
-    // ensures that we only resize as fast as we can paint.  We only need to
-    // send an ACK if we are resized to a non-empty rect.
-    webwidget_->resize(new_widget_size);
+  gfx::Size new_widget_size = size_;
+  if (IsUseZoomForDSFEnabled()) {
+    new_widget_size = gfx::ScaleToCeiledSize(new_widget_size,
+                                             GetOriginalDeviceScaleFactor());
   }
+  // When resizing, we want to wait to paint before ACK'ing the resize.  This
+  // ensures that we only resize as fast as we can paint.  We only need to
+  // send an ACK if we are resized to a non-empty rect.
+  webwidget_->resize(new_widget_size);
+
   WebSize visual_viewport_size;
 
   if (IsUseZoomForDSFEnabled()) {
     visual_viewport_size = gfx::ScaleToCeiledSize(
         params.visible_viewport_size,
         GetOriginalDeviceScaleFactor());
   } else {
     visual_viewport_size = visible_viewport_size_;
   }
 
@@ skipping 933 matching lines @@
 }
 
 float RenderWidget::GetOriginalDeviceScaleFactor() const {
   return
       screen_metrics_emulator_ ?
       screen_metrics_emulator_->original_screen_info().deviceScaleFactor :
       device_scale_factor_;
 }
 
 }  // namespace content