Added support for displaying the select folder picker in Chrome ASH on Windows 8.

win8/metro_driver/chrome_app_view_ash.h

Index: win8/metro_driver/chrome_app_view_ash.h
===================================================================
--- win8/metro_driver/chrome_app_view_ash.h	(revision 194196)
+++ win8/metro_driver/chrome_app_view_ash.h	(working copy)
@@ -22,6 +22,8 @@
 
 class OpenFilePickerSession;
 class SaveFilePickerSession;
+class FolderPickerSession;
+class FilePickerSessionBase;
 
 struct MetroViewerHostMsg_SaveAsDialogParams;
 
@@ -49,6 +51,7 @@
                                bool allow_multiple_files);
   void OnDisplayFileSaveAsDialog(
       const MetroViewerHostMsg_SaveAsDialogParams& params);
+  void OnDisplayFolderPicker(const string16& title);
 
   // This function is invoked when the open file operation completes. The
   // result of the operation is passed in along with the OpenFilePickerSession
@@ -64,6 +67,13 @@
   void OnSaveFileCompleted(SaveFilePickerSession* save_file_picker,
                            bool success);
 
+  // This function is invoked when the folder picker operation completes. The
+  // result of the operation is passed in along with the FolderPickerSession
+  // instance which is deleted after we read the required information from
+  // the FolderPickerSession class.
+  void OnFolderPickerCompleted(FolderPickerSession* folder_picker,
+                               bool success);
+
  private:
   HRESULT OnActivate(winapp::Core::ICoreApplicationView* view,
                      winapp::Activation::IActivatedEventArgs* args);
@@ -109,6 +119,7 @@
   EventRegistrationToken visibility_changed_token_;
   EventRegistrationToken accel_keydown_token_;
   EventRegistrationToken accel_keyup_token_;
+  EventRegistrationToken window_activated_token_;
 
   // Keep state about which button is currently down, if any, as PointerMoved
   // events do not contain that state, but Ash's MouseEvents need it.