Fix the double-tap to click gesture in touch accessibility mode.

ash/ash_touch_exploration_manager_chromeos.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 ASH_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_
 #define ASH_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_
 
 #include <memory>
 
 #include "ash/ash_export.h"
@@ skipping 34 matching lines @@
   void PlayExitScreenEarcon() override;
   void PlayEnterScreenEarcon() override;
   void HandleAccessibilityGesture(ui::AXGesture gesture) override;
 
   // aura::client::ActivationChangeObserver overrides:
   void OnWindowActivated(
       aura::client::ActivationChangeObserver::ActivationReason reason,
       aura::Window* gained_active,
       aura::Window* lost_active) override;
 
+  // Update the touch exploration controller so that synthesized touch
+  // events are anchored at this point.
+  void SetTouchAccessibilityAnchorPoint(const gfx::Point& anchor_point);
+
  private:
   void UpdateTouchExplorationState();
   bool VolumeAdjustSoundEnabled();
 
   std::unique_ptr<ui::TouchExplorationController> touch_exploration_controller_;
   RootWindowController* root_window_controller_;
   chromeos::CrasAudioHandler* audio_handler_;
 
   DISALLOW_COPY_AND_ASSIGN(AshTouchExplorationManager);
 };
 
 }  // namespace ash
 
 #endif  // ASH_TOUCH_EXPLORATION_MANAGER_CHROMEOS_H_