Enforce constant size and device scale factor for surfaces

cc/surfaces/compositor_frame_sink_support.cc

 // Copyright 2016 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/compositor_frame_sink_support.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "cc/output/compositor_frame.h"
@@ skipping 107 matching lines @@
                                "RenderWidgetHostImpl::OnSwapCompositorFrame")) {
     std::vector<ui::LatencyInfo>().swap(frame.metadata.latency_info);
   }
   for (ui::LatencyInfo& latency : frame.metadata.latency_info) {
     if (latency.latency_components().size() > 0) {
       latency.AddLatencyNumber(ui::DISPLAY_COMPOSITOR_RECEIVED_FRAME_COMPONENT,
                                0, 0);
     }
   }
 
+  SurfaceId surface_id(frame_sink_id_, local_surface_id);
+  gfx::Size frame_size = frame.render_pass_list.back()->output_rect.size();
+  float device_scale_factor = frame.metadata.device_scale_factor;
+  SurfaceInfo surface_info(surface_id, device_scale_factor, frame_size);
+  if (!surface_info.is_valid()) {
+    DLOG(ERROR) << "Cannot create a surface with invalid SurfaceInfo.";
+    if (current_surface_) {
+      current_surface_->RunDrawCallback();

[Fady Samuel, 2017/05/17 00:40:50]

Could you please add a comment why we need to do this? Do  we do this whenever
we replace a surface?

[Saman Sami, 2017/05/17 00:55:17]

It's already called in the destructor. My bad.

+      DestroyCurrentSurface();
+    }
+    ReturnedResourceArray resources;
+    TransferableResource::ReturnResources(frame.resource_list, &resources);
+    ReturnResources(resources);
+    DidReceiveCompositorFrameAck();
+    return;
+  }
+
   std::unique_ptr<Surface> surface;
   bool create_new_surface =
       (!current_surface_ ||
        local_surface_id != current_surface_->surface_id().local_surface_id());
   if (!create_new_surface) {
     surface = std::move(current_surface_);
   } else {
-    surface = CreateSurface(local_surface_id);
+    surface = CreateSurface(surface_info);
   }
 
   surface->QueueFrame(
       std::move(frame),
       base::Bind(&CompositorFrameSinkSupport::DidReceiveCompositorFrameAck,
                  weak_factory_.GetWeakPtr()),
       base::BindRepeating(&CompositorFrameSinkSupport::WillDrawSurface,
                           weak_factory_.GetWeakPtr()));
 
   if (current_surface_) {
@@ skipping 179 matching lines @@
     return;
 
   added_frame_observer_ = needs_begin_frame_;
   if (needs_begin_frame_)
     begin_frame_source_->AddObserver(this);
   else
     begin_frame_source_->RemoveObserver(this);
 }
 
 std::unique_ptr<Surface> CompositorFrameSinkSupport::CreateSurface(
-    const LocalSurfaceId& local_surface_id) {
+    const SurfaceInfo& surface_info) {
   seen_first_frame_activation_ = false;
-  std::unique_ptr<Surface> surface = surface_manager_->CreateSurface(
-      weak_factory_.GetWeakPtr(), local_surface_id);
+  std::unique_ptr<Surface> surface =
+      surface_manager_->CreateSurface(weak_factory_.GetWeakPtr(), surface_info);
   return surface;
 }
 
 void CompositorFrameSinkSupport::DestroyCurrentSurface() {
   surface_manager_->DestroySurface(std::move(current_surface_));
 }
 
 void CompositorFrameSinkSupport::RequestCopyOfSurface(
     std::unique_ptr<CopyOutputRequest> copy_request) {
   if (!current_surface_)
     return;
 
   DCHECK(current_surface_->compositor_frame_sink_support().get() == this);
   current_surface_->RequestCopyOfOutput(std::move(copy_request));
   surface_manager_->SurfaceModified(current_surface_->surface_id());
 }
 
 }  // namespace cc