Consolidate javascript_dialog_manager.h and javascript_dialog_manager_impl.h

components/app_modal/app_modal_dialog.h

Index: components/app_modal/app_modal_dialog.h
diff --git a/components/app_modal/app_modal_dialog.h b/components/app_modal/app_modal_dialog.h
index 7180d12d6860da9c0fed778cdb19ec8495840786..0c2b5dceee3a62e4cdad7544d58e45e6492c1f62 100644
--- a/components/app_modal/app_modal_dialog.h
+++ b/components/app_modal/app_modal_dialog.h
@@ -11,12 +11,14 @@
 #include "base/strings/string16.h"
 #include "build/build_config.h"
 
-class NativeAppModalDialog;
-
 namespace content {
 class WebContents;
 }
 
+namespace app_modal {
+
+class NativeAppModalDialog;
+
 // A controller+model base class for modal dialogs.
 class AppModalDialog {
  public:
@@ -102,4 +104,6 @@ class AppModalDialogObserver {
   DISALLOW_COPY_AND_ASSIGN(AppModalDialogObserver);
 };
 
+}  // namespace app_modal
+
 #endif  // COMPONENTS_APP_MODAL_APP_MODAL_DIALOG_H_