Avoid two targeting phases in aura client-lib and EventProcessor.

ui/aura/test/test_window_targeter.h

+// Copyright 2017 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_AURA_TEST_TEST_WINDOW_TARGETER_H_
+#define UI_AURA_TEST_TEST_WINDOW_TARGETER_H_
+
+#include "base/macros.h"
+#include "ui/aura/window_targeter.h"
+#include "ui/events/event_targeter.h"
+
+namespace aura {
+namespace test {
+
+class TestWindowTargeter : public WindowTargeter {
+ public:
+  TestWindowTargeter();
+  ~TestWindowTargeter() override;
+
+ protected:
+  // WindowTargeter:
+  ui::EventTarget* FindTargetForEvent(ui::EventTarget* root,
+                                      ui::Event* event) override;
+  ui::EventTarget* FindNextBestTarget(ui::EventTarget* previous_target,
+                                      ui::Event* event) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TestWindowTargeter);
+};
+
+}  // namespace test
+}  // namespace aura
+
+#endif  // UI_AURA_TEST_TEST_WINDOW_TARGETER_H_