Fix large mis-paint when resizing windows aura chrome

ui/compositor/compositor.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 "ui/compositor/compositor.h"
 
 #include <algorithm>
 #include <deque>
 
 #include "base/bind.h"
@@ skipping 392 matching lines @@
 Compositor::Compositor(CompositorDelegate* delegate,
                        gfx::AcceleratedWidget widget)
     : delegate_(delegate),
       root_layer_(NULL),
       widget_(widget),
       posted_swaps_(new PostedSwapQueue()),
       device_scale_factor_(0.0f),
       last_started_frame_(0),
       last_ended_frame_(0),
       disable_schedule_composite_(false),
+      is_resizing_ (false),
       compositor_lock_(NULL) {
   root_web_layer_ = cc::Layer::Create();
   root_web_layer_->SetAnchorPoint(gfx::PointF(0.f, 0.f));
 
   CommandLine* command_line = CommandLine::ForCurrentProcess();
   cc::LayerTreeSettings settings;
   settings.initialDebugState.show_fps_counter =
       command_line->HasSwitch(switches::kUIShowFPSCounter);
   settings.initialDebugState.show_platform_layer_tree =
       command_line->HasSwitch(switches::kUIShowLayerTree);
@@ skipping 66 matching lines @@
   root_web_layer_->RemoveAllChildren();
   if (root_layer_)
     root_web_layer_->AddChild(root_layer_->cc_layer());
 }
 
 void Compositor::SetHostHasTransparentBackground(
     bool host_has_transparent_background) {
   host_->set_has_transparent_background(host_has_transparent_background);
 }
 
+#if defined (OS_WIN)
+#ifndef NDEBUG
+const int kResizePaintLatency = 12 * 16;
+#else
+const int kResizePaintLatency = 4 * 16;
+#endif
+#endif  // OS_WIN.
+
 void Compositor::Draw(bool force_clear) {
   DCHECK(!g_compositor_thread);
 
   if (!root_layer_)
     return;
 
   last_started_frame_++;
   PendingSwap pending_swap(DRAW_SWAP, posted_swaps_.get());
   if (!IsLocked()) {
     // TODO(nduca): Temporary while compositor calls
     // compositeImmediately() directly.
     layout();
     host_->Composite(base::TimeTicks::Now());
+
+#if defined(OS_WIN)
+    // While we resize, we are usually a few frames behind. By blocking
+    // the UI thread here we minize the area that is mis-painted, specially
+    // in the non-client area. See RenderWidgetHostViewAura::SetBounds for
+    // more details.
+    if (is_resizing_ && (last_ended_frame_ > 1)) {

[cpu_(ooo_6.6-7.5), 2013/04/04 02:09:07]

when chrome starts we hit here with frames 0 and 1, so I check for that so that
I don't jank startup.

+      is_resizing_ = false;
+      base::PlatformThread::Sleep(
+          base::TimeDelta::FromMilliseconds(kResizePaintLatency));

[jonathan.backer, 2013/04/04 17:25:09]

My experience has been that there are a lot of events that bounce through the UI
thread. Blocking the UI thread for 50-200 ms is going to slow them down.

I'm familiar with the ResizeLock code. I'm going to get a win_aura build running
today (it's been months since I've built on windows --- I'll probably just pave
everything).

Once I understand the problem, hopefully I can be more constructive. A quick
glance at the code suggests we probably want to synchronize the
|root_web_layer_| SetBounds with the ResizeLock.

+    }
+#endif
+
   }
   if (!pending_swap.posted())
     NotifyEnd();
 }
 
 void Compositor::ScheduleFullDraw() {
   host_->SetNeedsRedraw();
 }
 
 bool Compositor::ReadPixels(SkBitmap* bitmap,
@@ skipping 10 matching lines @@
   PendingSwap pending_swap(READPIXELS_SWAP, posted_swaps_.get());
   return host_->CompositeAndReadback(pixels, bounds_in_pixel);
 }
 
 void Compositor::SetScaleAndSize(float scale, const gfx::Size& size_in_pixel) {
   DCHECK_GT(scale, 0);
   if (!size_in_pixel.IsEmpty()) {
     size_ = size_in_pixel;
     host_->SetViewportSize(size_in_pixel, size_in_pixel);
     root_web_layer_->SetBounds(size_in_pixel);
+
+    is_resizing_ = true;
   }
   if (device_scale_factor_ != scale) {
     device_scale_factor_ = scale;
     if (root_layer_)
       root_layer_->OnDeviceScaleFactorChanged(scale);
   }
 }
 
 void Compositor::AddObserver(CompositorObserver* observer) {
   observer_list_.AddObserver(observer);
@@ skipping 167 matching lines @@
 COMPOSITOR_EXPORT void DisableTestCompositor() {
   ResetImplicitFactory();
   g_test_compositor_enabled = false;
 }
 
 COMPOSITOR_EXPORT bool IsTestCompositorEnabled() {
   return g_test_compositor_enabled;
 }
 
 }  // namespace ui