Merge changes Id68b6c37,I16d39d3e into sc-dev

* changes:
  Fix a couple of crashes when taskbar isn't yet attached
  Subtract taskbar size from DeviceProfile#availableHeight

src/com/android/launcher3/util/DisplayController.java

@@ -197,6 +197,10 @@ public class DisplayController implements DisplayListener {
             return new Info(displayContext, display);
         }
 
+        public Context getDisplayContext() {
+            return mDisplayContext;
+        }
+
         protected void handleOnChange() {
             Info oldInfo = mInfo;
             Info newInfo = createInfoForContext(mDisplayContext);