chromecast: Cleanup class/struct fwd declarations

chromecast/browser/android/cast_window_manager.h

 // Copyright 2014 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 CHROMECAST_BROWSER_ANDROID_CAST_WINDOW_MANAGER_H_
 #define CHROMECAST_BROWSER_ANDROID_CAST_WINDOW_MANAGER_H_
 
 #include <jni.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/scoped_java_ref.h"
 
 class CastWindowAndroid;
 
-namespace content {
-class BrowserContext;
-}
-
 namespace chromecast {
 namespace shell {
 
 // Given a CastWindowAndroid instance, creates and returns a Java wrapper.
 base::android::ScopedJavaLocalRef<jobject>
 CreateCastWindowView(CastWindowAndroid* shell);
 
 // Closes a previously created Java wrapper.
 void CloseCastWindowView(jobject shell_wrapper);
 
 // Registers the CastWindowManager native methods.
 bool RegisterCastWindowManager(JNIEnv* env);
 
 }  // namespace shell
 }  // namespace chromecast
 
 #endif  // CHROMECAST_BROWSER_ANDROID_CAST_WINDOW_MANAGER_H_