components: Cleanup class/struct fwd declarations

chrome/browser/ui/android/javascript_app_modal_dialog_android.h

 // Copyright (c) 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.
 
 #ifndef CHROME_BROWSER_UI_ANDROID_JAVASCRIPT_APP_MODAL_DIALOG_ANDROID_H_
 #define CHROME_BROWSER_UI_ANDROID_JAVASCRIPT_APP_MODAL_DIALOG_ANDROID_H_
 
 #include <memory>
 
 #include "base/android/jni_weak_ref.h"
 #include "base/android/scoped_java_ref.h"
 #include "base/macros.h"
 #include "components/app_modal/native_app_modal_dialog.h"
 
+namespace app_modal {
 class JavaScriptAppModalDialog;
+}
 
 class JavascriptAppModalDialogAndroid
     : public app_modal::NativeAppModalDialog {
  public:
   JavascriptAppModalDialogAndroid(
       JNIEnv* env,
       app_modal::JavaScriptAppModalDialog* dialog,
       gfx::NativeWindow parent);
 
   // NativeAppModalDialog:
@@ skipping 25 matching lines @@
 
   std::unique_ptr<app_modal::JavaScriptAppModalDialog> dialog_;
   base::android::ScopedJavaGlobalRef<jobject> dialog_jobject_;
   JavaObjectWeakGlobalRef parent_jobject_weak_ref_;
 
   DISALLOW_COPY_AND_ASSIGN(JavascriptAppModalDialogAndroid);
 };
 
 
 #endif  // CHROME_BROWSER_UI_ANDROID_JAVASCRIPT_APP_MODAL_DIALOG_ANDROID_H_