Properly handle quick switch between Home button and Gallery app

This change fixes the following bug:

1. Playing a movie (especially Full HD) by Gallery.
2. Press the Home button.
3. Press the Gallery shortcut on Launcher.
4. Very quickly repeat #2 and #3 several times.

Result: "Sorry, this video cannot be played" alert is shown.

Change-Id: Idf9d222ca1e0bb90bfe06f6dc807dfbc71b6415b
Signed-off-by: Yuriy Zabroda <yuriy.zabroda@ti.com>

core/java/android/view/SurfaceView.java

@@ -531,7 +531,7 @@ public class SurfaceView extends View {
 
                     mSurface.transferFrom(mNewSurface);
 
-                    if (visible) {
+                    if (visible && mSurface.isValid()) {
                         if (!mSurfaceCreated && (surfaceChanged || visibleChanged)) {
                             mSurfaceCreated = true;
                             mIsCreating = true;