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

ash/root_window_controller.h

Index: ash/root_window_controller.h
diff --git a/ash/root_window_controller.h b/ash/root_window_controller.h
index 987f59ed3664cde723579b8460b8195876484c0d..ef62ccd8100df160e828bdca251ca18ebf478017 100644
--- a/ash/root_window_controller.h
+++ b/ash/root_window_controller.h
@@ -229,6 +229,10 @@ class ASH_EXPORT RootWindowController : public ShellObserver {
   // Tests if a window is associated with the virtual keyboard.
   bool IsVirtualKeyboardWindow(aura::Window* window);
 
+  // If touch exploration is enabled, update the touch exploration
+  // controller so that synthesized touch events are anchored at this point.
+  void SetTouchAccessibilityAnchorPoint(const gfx::Point& anchor_point);
+
  private:
   explicit RootWindowController(AshWindowTreeHost* host);
   enum RootWindowType {