Show voice button only on voice enabled devices

  Bug: 6686590

Change-Id: If3a79ec8b848d0c5d001e0c38de5973bb6a166a1
diff --git a/src/com/android/browser/NavigationBarTablet.java b/src/com/android/browser/NavigationBarTablet.java
index 79c8de6..adfd5e7 100644
--- a/src/com/android/browser/NavigationBarTablet.java
+++ b/src/com/android/browser/NavigationBarTablet.java
@@ -322,19 +322,19 @@
 
     @Override
     public void onStateChanged(int state) {
+        mVoiceButton.setVisibility(View.GONE);
         switch(state) {
         case STATE_NORMAL:
             mClearButton.setVisibility(View.GONE);
-            mVoiceButton.setVisibility(View.GONE);
-
             break;
         case STATE_HIGHLIGHTED:
             mClearButton.setVisibility(View.GONE);
-            mVoiceButton.setVisibility(View.VISIBLE);
+            if ((mUiController != null) && mUiController.supportsVoice()) {
+                mVoiceButton.setVisibility(View.VISIBLE);
+            }
             break;
         case STATE_EDITED:
             mClearButton.setVisibility(View.VISIBLE);
-            mVoiceButton.setVisibility(View.GONE);
             break;
         }
     }