Only focus the default item in the system tray when spoken feedback is enabled

BUG=315302

Review URL: https://codereview.chromium.org/60203005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233463 0039d316-1c4b-4281-b951-d872f2087c98

ash/system/tray/system_tray.cc

@@ -99,6 +99,11 @@ class SystemBubbleWrapper {
           views::BubbleBorder::PAINT_NONE);
     }
     is_persistent_ = is_persistent;
+
+    // If ChromeVox is enabled, focus the default item.
+    AccessibilityDelegate* delegate =
+        Shell::GetInstance()->accessibility_delegate();
+    if (delegate->IsSpokenFeedbackEnabled())
       bubble_->FocusDefault();
   }