Introduce the MaskedViewTargeter class

ui/views/masked_view_targeter.h

Index: ui/views/masked_view_targeter.h
diff --git a/ui/views/masked_view_targeter.h b/ui/views/masked_view_targeter.h
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+++ b/ui/views/masked_view_targeter.h
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+// 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_MASKED_VIEW_TARGETER_H_
+#define UI_VIEWS_MASKED_VIEW_TARGETER_H_
+
+#include "ui/views/view_targeter.h"
+#include "ui/views/views_export.h"
+
+namespace gfx {
+class Path;
+}
+
+namespace views {
+
+// Derived classes of MaskedViewTargeter are used to define custom-shaped
+// hit test regions for a View used in event targeting.
+// TODO(tdanderson|sadrul): Some refactoring opportunities may be possible
+//                          between this class and MaskedWindowTargeter.
+class VIEWS_EXPORT MaskedViewTargeter : public ViewTargeter {
+ public:
+  explicit MaskedViewTargeter(View* masked_view);
+  virtual ~MaskedViewTargeter();
+
+ protected:
+  // Sets the hit-test mask for |view| in |mask| (in |view|'s local
+  // coordinate system). Returns whether a valid mask has been set in |mask|.
+  virtual bool GetHitTestMask(View* view, gfx::Path* mask) const = 0;
+
+  // ui::EventTargeter:
+  virtual bool EventLocationInsideBounds(
+      ui::EventTarget* target,
+      const ui::LocatedEvent& event) const OVERRIDE;
+
+ private:
+  View* masked_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(MaskedViewTargeter);
+};
+
+}  // namespace views
+
+#endif  // UI_VIEWS_MASKED_VIEW_TARGETER_H_