Support targeting for gestures in ViewTargeter

ui/views/widget/root_view_targeter.h

+// 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.
+
+#ifndef UI_VIEWS_WIDGET_ROOT_VIEW_TARGETER_H_
+#define UI_VIEWS_WIDGET_ROOT_VIEW_TARGETER_H_
+
+#include "ui/views/view_targeter.h"
+#include "ui/views/views_export.h"
+
+namespace views {
+
+namespace internal {
+class RootView;
+}  // namespace internal
+
+class View;
+class ViewTargeterDelegate;
+
+// A derived class of ViewTargeter that defines targeting logic for cases
+// needing to access the members of RootView. For example, when determining the
+// target of a gesture event, we need to know if a previous gesture has already
+// established the View to which all subsequent gestures should be targeted.
+class VIEWS_EXPORT RootViewTargeter : public ViewTargeter {
+ public:
+  RootViewTargeter(ViewTargeterDelegate* delegate,
+                   internal::RootView* root_view);
+  virtual ~RootViewTargeter();
+
+ private:
+  // ViewTargeter:
+  virtual View* FindTargetForGestureEvent(
+      View* root,
+      const ui::GestureEvent& gesture) OVERRIDE;
+  virtual ui::EventTarget* FindNextBestTargetForGestureEvent(
+      ui::EventTarget* previous_target,
+      const ui::GestureEvent& gesture) OVERRIDE;
+
+  // A pointer to the RootView on which |this| is installed.
+  internal::RootView* root_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(RootViewTargeter);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_WIDGET_ROOT_VIEW_TARGETER_H_