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

ui/gl/android/scoped_java_surface.cc

Index: ui/gl/android/scoped_java_surface.cc
diff --git a/ui/gl/android/scoped_java_surface.cc b/ui/gl/android/scoped_java_surface.cc
index ae4f81a44bd82a23e9e83f0b5a9f4c7b0bea2e27..ff0862300acdf0ce4c963ac64d4f086fe4eb3d7d 100644
--- a/ui/gl/android/scoped_java_surface.cc
+++ b/ui/gl/android/scoped_java_surface.cc
@@ -75,6 +75,14 @@ bool ScopedJavaSurface::IsEmpty() const {
   return j_surface_.is_null();
 }
 
+bool ScopedJavaSurface::IsValid() const {
+  // Null surface are considered valid as it can be passed to a MediaPlayer.
+  if (IsEmpty())
+    return true;
+  JNIEnv* env = base::android::AttachCurrentThread();
+  return JNI_Surface::Java_Surface_isValid(env, j_surface_.obj());

[no sievers, 2015/10/08 23:00:27]

Are you sure we need to check this? Or is it good enough to reset surface_ to
null in SetVideoSurface (i.e. you other change)?

This *seems* odd, because we don't really do that anywhere else we deal with
Surfaces. Before it's released ContentVideoView.surfaceDestroyed() should cause
us to reset our reference.

[qinmin, 2015/10/08 23:47:23]

removed this function. When surfaceDestroyed() is called, setVideoSurface(null)
should be called. In that case, we can just set surface_ to surface(which is
null).

+}
+
 // static
 ScopedJavaSurface ScopedJavaSurface::AcquireExternalSurface(jobject surface) {
   JNIEnv* env = base::android::AttachCurrentThread();