cc::SurfaceDependencyTracker should not crash when a Display goes away

cc/surfaces/surface_manager.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/surface_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <queue>
@@ skipping 47 matching lines @@
   SurfaceReferencesToStringImpl(root_surface_id_, "", &str);
   // Temporary references will have an asterisk in front of them.
   for (auto& map_entry : temporary_references_)
     SurfaceReferencesToStringImpl(map_entry.first, "* ", &str);
 
   return str.str();
 }
 #endif
 
 void SurfaceManager::SetDependencyTracker(
-    std::unique_ptr<SurfaceDependencyTracker> dependency_tracker) {
-  dependency_tracker_ = std::move(dependency_tracker);
+    SurfaceDependencyTracker* dependency_tracker) {
+  dependency_tracker_ = dependency_tracker;
 }
 
 void SurfaceManager::RequestSurfaceResolution(Surface* pending_surface) {
   if (dependency_tracker_)
     dependency_tracker_->RequestSurfaceResolution(pending_surface);
 }
 
 std::unique_ptr<Surface> SurfaceManager::CreateSurface(
     base::WeakPtr<CompositorFrameSinkSupport> compositor_frame_sink_support,
     const SurfaceInfo& surface_info) {
@@ skipping 344 matching lines @@
 void SurfaceManager::RegisterBeginFrameSource(
     BeginFrameSource* source,
     const FrameSinkId& frame_sink_id) {
   framesink_manager_.RegisterBeginFrameSource(source, frame_sink_id);
 }
 
 void SurfaceManager::UnregisterBeginFrameSource(BeginFrameSource* source) {
   framesink_manager_.UnregisterBeginFrameSource(source);
 }
 
+BeginFrameSource* SurfaceManager::GetPrimaryBeginFrameSource() {
+  return framesink_manager_.GetPrimaryBeginFrameSource();
+}
+
 void SurfaceManager::RegisterFrameSinkHierarchy(
     const FrameSinkId& parent_frame_sink_id,
     const FrameSinkId& child_frame_sink_id) {
   framesink_manager_.RegisterFrameSinkHierarchy(parent_frame_sink_id,
                                                 child_frame_sink_id);
 }
 
 void SurfaceManager::UnregisterFrameSinkHierarchy(
     const FrameSinkId& parent_frame_sink_id,
     const FrameSinkId& child_frame_sink_id) {
@@ skipping 101 matching lines @@
     std::vector<SurfaceId> children(iter->second.begin(), iter->second.end());
     std::sort(children.begin(), children.end());
 
     for (const SurfaceId& child_id : children)
       SurfaceReferencesToStringImpl(child_id, indent + "  ", str);
   }
 }
 #endif  // DCHECK_IS_ON()
 
 }  // namespace cc