[aw] Fix crash when "misbehave" app exits fullscreen.

android_webview/java/src/org/chromium/android_webview/AwContents.java

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.android_webview;
 
 import android.annotation.SuppressLint;
 import android.app.Activity;
 import android.content.ComponentCallbacks2;
 import android.content.Context;
@@ skipping 645 matching lines @@
         setContainerView(fullScreenView);
 
         return fullScreenView;
     }
 
     /**
      * Returns this {@link AwContents} to embedded mode, where the {@link AwContents} are drawn
      * in the WebView.
      */
     void exitFullScreen() {
-        assert isFullScreen();
+        if (!isFullScreen())
+            // exitFullScreen() can be called without a prior call to enterFullScreen() if a
+            // "misbehave" app overrides onShowCustomView but does not add the custom view to
+            // the window. Exiting avoids a crash.
+            return;
 
         // Detach to tear down the GL functor if this is still associated with the old
         // container view. It will be recreated during the next call to onDraw attached to
         // the new container view.
         // NOTE: we cannot use mAwViewMethods here because its type is NullAwViewMethods.
         AwViewMethods awViewMethodsImpl = mFullScreenTransitionsState.getInitialAwViewMethods();
         awViewMethodsImpl.onDetachedFromWindow();
 
         // Swap the view delegates. In embedded mode the FullScreenView owns a
         // NullAwViewMethods and AwContents the AwViewMethodsImpl.
@@ skipping 1823 matching lines @@
 
     private native void nativeSetJsOnlineProperty(long nativeAwContents, boolean networkUp);
 
     private native void nativeTrimMemory(long nativeAwContents, int level, boolean visible);
 
     private native void nativeCreatePdfExporter(long nativeAwContents, AwPdfExporter awPdfExporter);
 
     private native void nativePreauthorizePermission(long nativeAwContents, String origin,
             long resources);
 }