Drive: Mount/Unmount GoogleDrive on Files App when the file system is mounted/unmounted.

chrome/browser/chromeos/gdata/gdata_system_service.cc

Index: chrome/browser/chromeos/gdata/gdata_system_service.cc
diff --git a/chrome/browser/chromeos/gdata/gdata_system_service.cc b/chrome/browser/chromeos/gdata/gdata_system_service.cc
index cdf10bf572e98391cd9ebc0e212f36965206f5d5..ba7874549148263f8e2bbbdaadc7125ce66fb2d7 100644
--- a/chrome/browser/chromeos/gdata/gdata_system_service.cc
+++ b/chrome/browser/chromeos/gdata/gdata_system_service.cc
@@ -115,9 +115,15 @@ void GDataSystemService::AddDriveMountPoint() {
         mount_point,
         new GDataFileSystemProxy(file_system_.get()));
   }
+
+  file_system_->Initialize();
+  file_system_->NotifyFileSystemMounted();
 }
 
 void GDataSystemService::RemoveDriveMountPoint() {
+  file_system_->NotifyFileSystemUnmounting();
+  file_system_->StopUpdates();
+
   const FilePath mount_point = gdata::util::GetGDataMountPointPath();
   fileapi::ExternalFileSystemMountPointProvider* provider =
       BrowserContext::GetFileSystemContext(profile_)->external_provider();