Implementated corner passthrough when touch exploration

 controller is on. 

If the user presses and holds the bottom right or left
 corner of the screen past a time delay, an earcon will
 sound, and then any subsequent fingers added onto the
 screen will send touch events as normal (passed through)
 as long as one finger is at a corner of the screen. Once
 the finger on the corner of the screen has lifted, then
 nothing will happen until all the fingers on the screen
 have been lifted.

UPDATE: Added earcons (short sound notifications) to
 indicate to the user if they have moved their finger off
 the screen or onto the screen or if they are in passthrough.
BUG=396310

Review URL: https://codereview.chromium.org/410783002

Cr-Commit-Position: refs/heads/master@{#289468}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@289468 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 0 deletions

diff --git a/ash/accessibility_delegate.h b/ash/accessibility_delegate.h
index 7dc2826..410ea7a 100644
--- a/ash/accessibility_delegate.h
+++ b/ash/accessibility_delegate.h
@@ -92,6 +92,11 @@ class ASH_EXPORT AccessibilityDelegate {
   // Gets the last accessibility alert that was triggered.
   virtual AccessibilityAlert GetLastAccessibilityAlert() = 0;
 
+  // Plays an earcon. Earcons are brief and distinctive sounds that indicate
+  // when their mapped event has occurred. The sound key enums can be found in
+  // chromeos/audio/chromeos_sounds.h.
+  virtual void PlayEarcon(int sound_key) = 0;
+
   // Initiates play of shutdown sound and returns it's duration.
   virtual base::TimeDelta PlayShutdownSound() const = 0;
 };