fast_ink: Fix DeleteWhenLastResourceHasBeenReclaimed.

Monitor the root window instead of the aura env to determine
when frame sink holder must be cleaned up. It's too late to
cleanup the holder when aura is being shutdown.

Bug: 814908
Test: Close chrome while fast ink view is visible.
Change-Id: Ia807c9469d791e4d8d4973711cf904592bc05471
Reviewed-on: https://chromium-review.googlesource.com/957222Reviewed-by: Vladislav Kaznacheev <kaznacheev@chromium.org>
Commit-Queue: David Reveman <reveman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542179}

ash/components/fast_ink/fast_ink_view.cc

@@ -20,8 +20,8 @@
 #include "gpu/command_buffer/client/gles2_interface.h"
 #include "gpu/command_buffer/client/gpu_memory_buffer_manager.h"
 #include "ui/aura/env.h"
-#include "ui/aura/env_observer.h"
 #include "ui/aura/window.h"
+#include "ui/aura/window_observer.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/layout.h"
 #include "ui/gfx/geometry/dip_util.h"
@@ -118,7 +118,7 @@ struct FastInkView::Resource {
 
 class FastInkView::LayerTreeFrameSinkHolder
     : public cc::LayerTreeFrameSinkClient,
-      public aura::EnvObserver {
+      public aura::WindowObserver {
  public:
   LayerTreeFrameSinkHolder(FastInkView* view,
                            std::unique_ptr<cc::LayerTreeFrameSink> frame_sink)
@@ -128,8 +128,8 @@ class FastInkView::LayerTreeFrameSinkHolder
   ~LayerTreeFrameSinkHolder() override {
     if (frame_sink_)
       frame_sink_->DetachFromClient();
-    if (env_)
-      env_->RemoveObserver(this);
+    if (root_window_)
+      root_window_->RemoveObserver(this);
   }
 
   // Delete frame sink after having reclaimed all exported resources.
@@ -165,15 +165,20 @@ class FastInkView::LayerTreeFrameSinkHolder
     if (holder->exported_resources_.empty())
       return;
 
-    aura::Env* env = aura::Env::GetInstance();
-    holder->env_ = env;
+    // Delete sink holder immediately if native window is already gone.
+    aura::Window* window = holder->view_->GetWidget()->GetNativeView();
+    if (!window)
+      return;
+
+    aura::Window* root_window = window->GetRootWindow();
+    holder->root_window_ = root_window;
     holder->view_ = nullptr;
 
     // If we have exported resources to reclaim then extend the lifetime of
-    // holder by adding it as an aura env observer. The holder will delete
-    // itself when aura shuts down or when all exported resources have been
-    // reclaimed.
-    env->AddObserver(holder.release());
+    // holder by adding it as a root window observer. The holder will delete
+    // itself when the root window is removed or when all exported resources
+    // have been reclaimed.
+    root_window->AddObserver(holder.release());
   }
 
   void SubmitCompositorFrame(viz::CompositorFrame frame,
@@ -204,7 +209,7 @@ class FastInkView::LayerTreeFrameSinkHolder
         view_->ReclaimResource(std::move(resource));
     }
 
-    if (env_ && exported_resources_.empty())
+    if (root_window_ && exported_resources_.empty())
       ScheduleDelete();
   }
   void SetTreeActivationCallback(const base::Closure& callback) override {}
@@ -219,7 +224,7 @@ class FastInkView::LayerTreeFrameSinkHolder
   void DidDiscardCompositorFrame(uint32_t presentation_token) override {}
   void DidLoseLayerTreeFrameSink() override {
     exported_resources_.clear();
-    if (env_)
+    if (root_window_)
       ScheduleDelete();
   }
   void OnDraw(const gfx::Transform& transform,
@@ -230,11 +235,10 @@ class FastInkView::LayerTreeFrameSinkHolder
       const gfx::Rect& viewport_rect,
       const gfx::Transform& transform) override {}
 
-  // Overridden from aura::EnvObserver:
-  void OnWindowInitialized(aura::Window* window) override {}
-  void OnWillDestroyEnv() override {
-    env_->RemoveObserver(this);
-    env_ = nullptr;
+  // Overridden from aura::WindowObserver:
+  void OnWindowDestroying(aura::Window* window) override {
+    root_window_->RemoveObserver(this);
+    root_window_ = nullptr;
     // Make sure frame sink never outlives aura.
     frame_sink_->DetachFromClient();
     frame_sink_.reset();
@@ -255,7 +259,7 @@ class FastInkView::LayerTreeFrameSinkHolder
       exported_resources_;
   gfx::Size last_frame_size_in_pixels_;
   float last_frame_device_scale_factor_ = 1.0f;
-  aura::Env* env_ = nullptr;
+  aura::Window* root_window_ = nullptr;
   bool delete_pending_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeFrameSinkHolder);