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

ui/metro_viewer/metro_viewer_messages.h

Index: ui/metro_viewer/metro_viewer_messages.h
===================================================================
--- ui/metro_viewer/metro_viewer_messages.h	(revision 194196)
+++ ui/metro_viewer/metro_viewer_messages.h	(working copy)
@@ -73,18 +73,22 @@
 // Informs the browser of the result of a file save as operation.
 IPC_MESSAGE_CONTROL3(MetroViewerHostMsg_FileSaveAsDone,
                      bool,           /* success */
-                     string16,       /* filename */
+                     base::FilePath, /* filename */
                      int)            /* filter_index */
 
 // Informs the browser of the result of a file open operation.
 IPC_MESSAGE_CONTROL2(MetroViewerHostMsg_FileOpenDone,
                      bool,           /* success */
-                     string16)       /* filename */
+                     base::FilePath) /* filename */
 
 IPC_MESSAGE_CONTROL2(MetroViewerHostMsg_MultiFileOpenDone,
                      bool,                    /* success */
                      std::vector<base::FilePath>)   /* filenames */
 
+// Informs the browser of the result of a select folder operation.
+IPC_MESSAGE_CONTROL2(MetroViewerHostMsg_SelectFolderDone,
+                     bool,           /* success */
+                     base::FilePath) /* filepath*/
 
 // Messages sent from the browser to the viewer:
 
@@ -100,7 +104,7 @@
   IPC_STRUCT_MEMBER(string16, title)
 
   // The suggested file name.
-  IPC_STRUCT_MEMBER(string16, suggested_name)
+  IPC_STRUCT_MEMBER(base::FilePath, suggested_name)
 
   // The save as filter to be used.
   IPC_STRUCT_MEMBER(string16, filter)
@@ -119,8 +123,11 @@
 
 // Requests the viewer to display the file open dialog.
 IPC_MESSAGE_CONTROL4(MetroViewerHostMsg_DisplayFileOpen,
-                     string16,   /* title */
-                     string16,   /* filter */
-                     string16,   /* Default path */
-                     bool)       /* allow_multi_select */
+                     string16,       /* title */
+                     string16,       /* filter */
+                     base::FilePath, /* Default path */
+                     bool)           /* allow_multi_select */
 
+// Requests the viewer to display the select folder dialog.
+IPC_MESSAGE_CONTROL1(MetroViewerHostMsg_DisplaySelectFolder,
+                     string16)   /* title */