Fire accessibilityPrivate events on two-finger hold gesture.

ash/default_accessibility_delegate.h

Index: ash/default_accessibility_delegate.h
diff --git a/ash/default_accessibility_delegate.h b/ash/default_accessibility_delegate.h
index 749abf3dd21e021dfd0254f8a4f104568972c3ac..8ef719b971eba8b64688c8ed1cada24f77d29fd1 100644
--- a/ash/default_accessibility_delegate.h
+++ b/ash/default_accessibility_delegate.h
@@ -56,6 +56,8 @@ class ASH_EXPORT DefaultAccessibilityDelegate : public AccessibilityDelegate {
   double GetSavedScreenMagnifierScale() override;
   void TriggerAccessibilityAlert(AccessibilityAlert alert) override;
   AccessibilityAlert GetLastAccessibilityAlert() override;
+  void OnTwoFingerTouchStart() override;
+  void OnTwoFingerTouchStop() override;

[oshima, 2017/04/10 18:32:08]

do you need these?

[dmazzoni, 2017/04/11 05:49:40]

No. Looks like an opportunity for cleanup, as most of these
aren't needed.

   bool ShouldToggleSpokenFeedbackViaTouch() override;
   void PlaySpokenFeedbackToggleCountdown(int tick_count) override;
   void PlayEarcon(int sound_key) override;