Fix an issue that an invalid surface could be passed to MediaPlayerBridge

ui/gl/android/scoped_java_surface.h

 // Copyright (c) 2013 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.
 
 #ifndef UI_GL_ANDROID_SCOPED_JAVA_SURFACE_H_
 #define UI_GL_ANDROID_SCOPED_JAVA_SURFACE_H_
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
@@ skipping 24 matching lines @@
   // the latter no longer owns the surface afterwards.
   ScopedJavaSurface(RValue rvalue);
   ScopedJavaSurface& operator=(RValue rhs);
 
   // Creates a ScopedJavaSurface that is owned externally, i.e.,
   // someone else is responsible to call Surface.release().
   static ScopedJavaSurface AcquireExternalSurface(jobject surface);
 
   ~ScopedJavaSurface();
 
-  // Check whether the surface is an empty one.
+  // Checks whether the surface is an empty one.
   bool IsEmpty() const;
 
-  // Check whether the surface is hardware protected so that no readback is
+  // Checks whether the surface is valid.
+  bool IsValid() const;
+
+  // Checks whether the surface is hardware protected so that no readback is
   // possible.
   bool is_protected() const { return is_protected_; }
 
   const base::android::JavaRef<jobject>& j_surface() const {
     return j_surface_;
   }
 
  private:
   // Performs destructive move from |other| to this.
   void MoveFrom(ScopedJavaSurface& other);
 
   bool auto_release_;
   bool is_protected_;
 
   base::android::ScopedJavaGlobalRef<jobject> j_surface_;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_ANDROID_SCOPED_JAVA_SURFACE_H_