[TTS] Add onTouchDown to GestureStateListener.

content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java

Index: content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java
diff --git a/content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java b/content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java
index 2854b35084bf5a1ffb26731527daf0a5a202a88f..4b7f89c28c595098736430cd12bca3a06ac8fdc0 100644
--- a/content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java
+++ b/content/public/android/java/src/org/chromium/content_public/browser/GestureStateListener.java
@@ -37,33 +37,39 @@ public class GestureStateListener {
      */
     public void onScrollUpdateGestureConsumed() {}
 
-    /*
+    /**
      * Called when a scroll gesture has started.
      */
     public void onScrollStarted(int scrollOffsetY, int scrollExtentY) {}
 
-    /*
+    /**
      * Called when a scroll gesture has stopped.
      */
     public void onScrollEnded(int scrollOffsetY, int scrollExtentY) {}
 
-    /*
+    /**
      * Called when the min or max scale factor may have been changed.
      */
     public void onScaleLimitsChanged(float minPageScaleFactor, float maxPageScaleFactor) {}
 
-    /*
+    /**
      * Called when the scroll offsets or extents may have changed.
      */
     public void onScrollOffsetOrExtentChanged(int scrollOffsetY, int scrollExtentY) {}
 
-    /*
+    /**
+     * Called at the beginning of any kind of touch event when the user's finger first touches down
+     * onto the screen.  The resulting gesture may be a single tap, long-press, or scroll.
+     */
+    public void onTouchDown() {}
+
+    /**
      * Called after a single-tap gesture event was dispatched to the renderer,
      * indicating whether or not the gesture was consumed.
      */
     public void onSingleTap(boolean consumed) {}
 
-    /*
+    /**
      * Called after a single-tap gesture event was processed by the renderer,
      * but was not handled.
      */