Enforce constant size and device scale factor for surfaces

cc/surfaces/direct_compositor_frame_sink.cc

 // Copyright 2014 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 "cc/surfaces/direct_compositor_frame_sink.h"
 
 #include "base/bind.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_sink_client.h"
 #include "cc/surfaces/display.h"
@@ skipping 81 matching lines @@
 
   CompositorFrameSink::DetachFromClient();
 }
 
 void DirectCompositorFrameSink::SubmitCompositorFrame(CompositorFrame frame) {
   DCHECK(frame.metadata.begin_frame_ack.has_damage);
   DCHECK_LE(BeginFrameArgs::kStartingFrameNumber,
             frame.metadata.begin_frame_ack.sequence_number);
 
   gfx::Size frame_size = frame.render_pass_list.back()->output_rect.size();
-  if (frame_size.IsEmpty() || frame_size != last_swap_frame_size_) {
-    delegated_local_surface_id_ = local_surface_id_allocator_.GenerateId();
+  if (!local_surface_id_.is_valid() || frame_size != last_swap_frame_size_ ||
+      frame.metadata.device_scale_factor != device_scale_factor_) {
+    local_surface_id_ = local_surface_id_allocator_.GenerateId();
     last_swap_frame_size_ = frame_size;
+    device_scale_factor_ = frame.metadata.device_scale_factor;
+    display_->SetLocalSurfaceId(local_surface_id_, device_scale_factor_);
   }
-  display_->SetLocalSurfaceId(delegated_local_surface_id_,
-                              frame.metadata.device_scale_factor);
 
-  support_->SubmitCompositorFrame(delegated_local_surface_id_,
-                                  std::move(frame));
+  bool result =
+      support_->SubmitCompositorFrame(local_surface_id_, std::move(frame));
+  DCHECK(result);
 }
 
 void DirectCompositorFrameSink::DisplayOutputSurfaceLost() {
   is_lost_ = true;
   client_->DidLoseCompositorFrameSink();
 }
 
 void DirectCompositorFrameSink::DisplayWillDrawAndSwap(
     bool will_draw_and_swap,
     const RenderPassList& render_passes) {
@@ skipping 31 matching lines @@
   support_->SetNeedsBeginFrame(needs_begin_frame);
 }
 
 void DirectCompositorFrameSink::OnDidFinishFrame(const BeginFrameAck& ack) {
   // If there was damage, SubmitCompositorFrame includes the ack.
   if (!ack.has_damage)
     support_->BeginFrameDidNotSwap(ack);
 }
 
 }  // namespace cc