Ensure Surface size always matches window size on swap

cc/surfaces/display.cc

Index: cc/surfaces/display.cc
diff --git a/cc/surfaces/display.cc b/cc/surfaces/display.cc
index a8ae27a6055f63c6b7f366c38881c4ec49435ae9..1a4ce76f175175dde22d3c21c7bcfe4fc1bab176 100644
--- a/cc/surfaces/display.cc
+++ b/cc/surfaces/display.cc
@@ -49,15 +49,21 @@ bool Display::Initialize(scoped_ptr<OutputSurface> output_surface) {
   return output_surface_->BindToClient(this);
 }
 
-void Display::Resize(SurfaceId id,
-                     const gfx::Size& size,
-                     float device_scale_factor) {
+void Display::SetSurfaceId(SurfaceId id, float device_scale_factor) {
   current_surface_id_ = id;
-  current_surface_size_ = size;
   device_scale_factor_ = device_scale_factor;
   client_->DisplayDamaged();
 }
 
+void Display::Resize(const gfx::Size& size) {
+  if (size == current_surface_size_)
+    return;
+  if (renderer_)
+    renderer_->Finish();

[jamesr, 2014/12/02 00:04:17]

add a comment here indicating why we need to finish()

we only really need to do this on windows, right? could we make this
configurable so we don't pay this cost on other platforms?

+  current_surface_size_ = size;
+  client_->DisplayDamaged();
+}
+
 void Display::InitializeRenderer() {
   if (resource_provider_)
     return;
@@ -112,6 +118,10 @@ bool Display::Draw() {
   benchmark_instrumentation::IssueDisplayRenderingStatsEvent();
   DelegatedFrameData* frame_data = frame->delegated_frame_data.get();
 
+  gfx::Size surface_size;
+  if (!frame_data->render_pass_list.empty())

[jamesr, 2014/12/02 00:04:17]

hmm, maybe Aggregate() should return a null frame if it ended up with an empty
pass list

+    surface_size = frame_data->render_pass_list.back()->output_rect.size();
+
   gfx::Rect device_viewport_rect = gfx::Rect(current_surface_size_);
   gfx::Rect device_clip_rect = device_viewport_rect;
   bool disable_picture_quad_image_filtering = false;
@@ -122,7 +132,14 @@ bool Display::Draw() {
                        device_viewport_rect,
                        device_clip_rect,
                        disable_picture_quad_image_filtering);
-  renderer_->SwapBuffers(frame->metadata);
+
+  if (surface_size == current_surface_size_) {
+    renderer_->SwapBuffers(frame->metadata);
+  } else {
+    DidSwapBuffers();
+    DidSwapBuffersComplete();

[piman, 2014/12/01 23:42:09]

Do we need to respect order wrt surface callbacks below?

+  }
+
   for (SurfaceAggregator::SurfaceIndexMap::iterator it =
            aggregator_->previous_contained_surfaces().begin();
        it != aggregator_->previous_contained_surfaces().end();