Change condition to enter silent mode.

Previously, silent mode was entered if volume was already at 0 and
volume down key was pressed once.

The new volume management policy specifies that silent mode is entered when
volume is at last audible step and volume down key is pressed once.

Change-Id: Id3e75a99c522d8afe276868010b6e73495d23fde
diff --git a/media/java/android/media/AudioService.java b/media/java/android/media/AudioService.java
index bfc6b5d..843afde 100644
--- a/media/java/android/media/AudioService.java
+++ b/media/java/android/media/AudioService.java
@@ -1558,21 +1558,29 @@
     private boolean checkForRingerModeChange(int oldIndex, int direction) {
         boolean adjustVolumeIndex = true;
         int newRingerMode = mRingerMode;
+        int uiIndex = (oldIndex + 5) / 10;
 
         if (mRingerMode == AudioManager.RINGER_MODE_NORMAL) {
-            // audible mode, at the bottom of the scale
-            if ((direction == AudioManager.ADJUST_LOWER &&
-                 mPrevVolDirection != AudioManager.ADJUST_LOWER) &&
-                ((oldIndex + 5) / 10 == 0)) {
-                // "silent mode", but which one?
-                newRingerMode = System.getInt(mContentResolver, System.VIBRATE_IN_SILENT, 1) == 1
-                    ? AudioManager.RINGER_MODE_VIBRATE
-                    : AudioManager.RINGER_MODE_SILENT;
+            if ((direction == AudioManager.ADJUST_LOWER) && (uiIndex <= 1)) {
+                // enter silent mode if current index is the last audible one and not repeating a
+                // volume key down
+                if (mPrevVolDirection != AudioManager.ADJUST_LOWER) {
+                    // "silent mode", but which one?
+                    newRingerMode = System.getInt(mContentResolver, System.VIBRATE_IN_SILENT, 1) == 1
+                        ? AudioManager.RINGER_MODE_VIBRATE
+                        : AudioManager.RINGER_MODE_SILENT;
+                }
+                if (uiIndex == 0) {
+                    adjustVolumeIndex = false;
+                }
             }
         } else {
             if (direction == AudioManager.ADJUST_RAISE) {
                 // exiting silent mode
                 newRingerMode = AudioManager.RINGER_MODE_NORMAL;
+                if (uiIndex != 0) {
+                    adjustVolumeIndex = false;
+                }
             } else {
                 // prevent last audible index to reach 0
                 adjustVolumeIndex = false;
@@ -1581,13 +1589,6 @@
 
         if (newRingerMode != mRingerMode) {
             setRingerMode(newRingerMode);
-
-            /*
-             * If we are changing ringer modes, do not increment/decrement the
-             * volume index. Instead, the handler for the message above will
-             * take care of changing the index.
-             */
-            adjustVolumeIndex = false;
         }
 
         mPrevVolDirection = direction;