Fix resize ACK bug

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 <set>
 #include <utility>
 
@@ skipping 573 matching lines @@
     resize_params->physical_backing_size = view_->GetPhysicalBackingSize();
     resize_params->top_controls_height = view_->GetTopControlsHeight();
     resize_params->top_controls_shrink_blink_size =
         view_->DoTopControlsShrinkBlinkSize();
     resize_params->visible_viewport_size = view_->GetVisibleViewportSize();
     resize_params->is_fullscreen = IsFullscreen();
   }
 
   const bool size_changed =
       !old_resize_params_ ||
-      old_resize_params_->new_size != resize_params->new_size;
+      current_size_ != resize_params->new_size;
   bool dirty =
       size_changed || screen_info_out_of_date_ ||
       old_resize_params_->physical_backing_size !=
           resize_params->physical_backing_size ||
       old_resize_params_->is_fullscreen != resize_params->is_fullscreen ||
       old_resize_params_->top_controls_height !=
           resize_params->top_controls_height ||
       old_resize_params_->top_controls_shrink_blink_size !=
           resize_params->top_controls_shrink_blink_size ||
       old_resize_params_->visible_viewport_size !=
@@ skipping 26 matching lines @@
 
   scoped_ptr<ViewMsg_Resize_Params> params(new ViewMsg_Resize_Params);
   if (!GetResizeParams(params.get()))
     return;
 
   bool width_changed =
       !old_resize_params_ ||
       old_resize_params_->new_size.width() != params->new_size.width();
   if (Send(new ViewMsg_Resize(routing_id_, *params))) {
     resize_ack_pending_ = params->needs_resize_ack;
+    DCHECK_IMPLIES(params->new_size.IsEmpty(), !params->needs_resize_ack);
+    if (params->new_size.IsEmpty())

[no sievers, 2015/02/26 00:23:06]

This is purely to make one of the tests happy which verifies that setting the
bounds to the same empty rect repeatedly does not send redundant updates.

I went back and forth on this :)
So we could also set |current_size_| to |new_size| here always if
|!needs_resize_ack|. But then we would end up skipping the ack for the case I
was originally trying to address, i.e. when the view bounds are already nonzero
and physical backing size becomes nonzero. Since that implies a paint it's maybe
better to throttle then.

+      current_size_ = params->new_size;
     old_resize_params_.swap(params);
   }
 
   if (delegate_)
     delegate_->RenderWidgetWasResized(this, width_changed);
 }
 
 void RenderWidgetHostImpl::ResizeRectChanged(const gfx::Rect& new_rect) {
   Send(new ViewMsg_ChangeResizeRect(routing_id_, new_rect));
 }
@@ skipping 1540 matching lines @@
 }
 #endif
 
 SkColorType RenderWidgetHostImpl::PreferredReadbackFormat() {
   if (view_)
     return view_->PreferredReadbackFormat();
   return kN32_SkColorType;
 }
 
 }  // namespace content