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

content/renderer/render_widget.cc

Index: content/renderer/render_widget.cc
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 896f57c81f33599c80e4905bf378c5b4af0a8322..f55471a5e77f41e8a724b9c9be75a35846f7fa38 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -688,6 +688,8 @@ void RenderWidget::OnWasShown(bool needs_repainting,
 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() {
@@ -1149,9 +1151,6 @@ void RenderWidget::Resize(const ResizeParams& params) {
   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;
 
@@ -1169,17 +1168,16 @@ void RenderWidget::Resize(const ResizeParams& params) {
   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()) {