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

cc/surfaces/surface_manager.h

Index: cc/surfaces/surface_manager.h
diff --git a/cc/surfaces/surface_manager.h b/cc/surfaces/surface_manager.h
index 34a2f3920573df46b045226a432a611b7de791e7..293f4c8af80a037f6c3660f08cd02cb4b640e161 100644
--- a/cc/surfaces/surface_manager.h
+++ b/cc/surfaces/surface_manager.h
@@ -59,8 +59,11 @@
   std::string SurfaceReferencesToString();
 #endif
 
-  void SetDependencyTracker(SurfaceDependencyTracker* dependency_tracker);
-  SurfaceDependencyTracker* dependency_tracker() { return dependency_tracker_; }
+  void SetDependencyTracker(
+      std::unique_ptr<SurfaceDependencyTracker> dependency_tracker);
+  SurfaceDependencyTracker* dependency_tracker() {
+    return dependency_tracker_.get();
+  }
 
   void RequestSurfaceResolution(Surface* pending_surface);
 
@@ -137,10 +140,6 @@
   void RegisterBeginFrameSource(BeginFrameSource* source,
                                 const FrameSinkId& frame_sink_id);
   void UnregisterBeginFrameSource(BeginFrameSource* source);
-
-  // Returns a stable BeginFrameSource that forwards BeginFrames from the first
-  // available BeginFrameSource.
-  BeginFrameSource* GetPrimaryBeginFrameSource();
 
   // Register a relationship between two namespaces.  This relationship means
   // that surfaces from the child namespace will be displayed in the parent.
@@ -289,7 +288,7 @@
   std::unordered_map<FrameSinkId, std::vector<LocalSurfaceId>, FrameSinkIdHash>
       temporary_reference_ranges_;
 
-  SurfaceDependencyTracker* dependency_tracker_ = nullptr;
+  std::unique_ptr<SurfaceDependencyTracker> dependency_tracker_;
 
   base::WeakPtrFactory<SurfaceManager> weak_factory_;