Fixed Camera2 crash on first camera start.

When camera enters video preview mode, it uses current window
size to select the best matching video preview size to request
from the camera HAL.

However, if video preview mode is the initial mode in which the
camera starts, there's a race condition between preview size
selection and camera app layout completion. If preview size
selection code is run first, it will get zero window size and
subsequently will crash.

It's not clear what's really the "best" fix in this situation
(= waiting for layout to complete would introduce extra latency
in the camera startup process), so current work-around just checks
whether window size is already defined and if not - uses display
size instead. This makes sense because normally camera window
is running full-screen anyway, so window size will match display
size.

Change-Id: Ie8555025902ba8ae6f719d45371145126290bb7c

src/com/android/camera/VideoUI.java

@@ -19,6 +19,7 @@
 import android.graphics.Bitmap;
 import android.graphics.Point;
 import android.graphics.SurfaceTexture;
+import android.util.DisplayMetrics;
 import android.view.GestureDetector;
 import android.view.MotionEvent;
 import android.view.View;
@@ -246,7 +247,17 @@ public void showPassiveFocusIndicator() {
      * @return The size of the available preview area.
      */
     public Point getPreviewScreenSize() {
-        return new Point(mRootView.getMeasuredWidth(), mRootView.getMeasuredHeight());
+        if (mRootView.getMeasuredWidth() > 0 && mRootView.getMeasuredHeight() > 0) {
+            return new Point(mRootView.getMeasuredWidth(), mRootView.getMeasuredHeight());
+	} else {
+	    // Measured width and height are not yet available - use screen size
+	    // as a proxy, should be fine given camera typically is full screen anyhow.
+	    DisplayMetrics metrics = new DisplayMetrics();
+	    mActivity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
+	    Log.i(TAG, "Measured width and height are not yet available, reverting " +
+	            "to display size: " + metrics.widthPixels + ", " + metrics.heightPixels);
+	    return new Point(metrics.widthPixels, metrics.heightPixels);
+	}
     }
 
     /**