Wire FileSystemOperation::TouchFile to Drive.

chrome/browser/chromeos/gdata/drive_file_system_proxy.h

Index: chrome/browser/chromeos/gdata/drive_file_system_proxy.h
diff --git a/chrome/browser/chromeos/gdata/drive_file_system_proxy.h b/chrome/browser/chromeos/gdata/drive_file_system_proxy.h
index 0c63eb0deb4617fe2402bbace0f03e66947f7c6a..88eb045b0fa5f695ff2570176617993b085b7269 100644
--- a/chrome/browser/chromeos/gdata/drive_file_system_proxy.h
+++ b/chrome/browser/chromeos/gdata/drive_file_system_proxy.h
@@ -77,7 +77,12 @@ class DriveFileSystemProxy : public fileapi::RemoteFileSystemProxyInterface {
       const fileapi::FileSystemOperation::OpenFileCallback&
           callback) OVERRIDE;
   virtual void NotifyCloseFile(const fileapi::FileSystemURL& url) OVERRIDE;
-  // TODO(zelidrag): More methods to follow as we implement other parts of FSO.
+  virtual void TouchFile(
+      const fileapi::FileSystemURL& url,
+      const base::Time& last_access_time,
+      const base::Time& last_modified_time,
+      const fileapi::FileSystemOperation::StatusCallback& callback)
+          OVERRIDE;
 
  protected:
   virtual ~DriveFileSystemProxy();