Use WeakPtr to RenderWidgetHostViewBase in InputEventRouter.

content/browser/renderer_host/render_widget_host_input_event_router.h

 // Copyright 2015 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.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_INPUT_EVENT_ROUTER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_INPUT_EVENT_ROUTER_H_
 
 #include <stdint.h>
 
 #include "base/containers/hash_tables.h"
+#include "base/memory/weak_ptr.h"
 #include "content/common/content_export.h"
 
 namespace blink {
 class WebMouseEvent;
 class WebMouseWheelEvent;
 class WebTouchEvent;
 }
 
 namespace gfx {
 class Point;
@@ skipping 27 matching lines @@
                        const ui::LatencyInfo& latency);
 
   void AddSurfaceIdNamespaceOwner(uint32_t id, RenderWidgetHostViewBase* owner);
   void RemoveSurfaceIdNamespaceOwner(uint32_t id);
 
   bool is_registered(uint32_t id) {
     return owner_map_.find(id) != owner_map_.end();
   }
 
  private:
+  using SurfaceIdNamespaceOwnerMap =
+      base::hash_map<uint32_t, base::WeakPtr<RenderWidgetHostViewBase>>;
+
   RenderWidgetHostViewBase* FindEventTarget(RenderWidgetHostViewBase* root_view,
                                             const gfx::Point& point,
                                             gfx::Point* transformed_point);
 
-  typedef base::hash_map<uint32_t, RenderWidgetHostViewBase*>
-      SurfaceIdNamespaceOwnerMap;
   SurfaceIdNamespaceOwnerMap owner_map_;
   RenderWidgetHostViewBase* current_touch_target_;
   int active_touches_;
 
   DISALLOW_COPY_AND_ASSIGN(RenderWidgetHostInputEventRouter);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDER_WIDGET_HOST_INPUT_EVENT_ROUTER_H_