Set root resource ID upon full feed update.

chrome/browser/chromeos/drive/drive_resource_metadata.cc

Index: chrome/browser/chromeos/drive/drive_resource_metadata.cc
diff --git a/chrome/browser/chromeos/drive/drive_resource_metadata.cc b/chrome/browser/chromeos/drive/drive_resource_metadata.cc
index fa144cc24aad923dcf9736b35ec7643645aa3a07..1d1e93448c6463c9f707407c07e302d152bbe947 100644
--- a/chrome/browser/chromeos/drive/drive_resource_metadata.cc
+++ b/chrome/browser/chromeos/drive/drive_resource_metadata.cc
@@ -221,6 +221,8 @@ scoped_ptr<DriveDirectory> DriveResourceMetadata::CreateDriveDirectory() {
 }
 
 void DriveResourceMetadata::InitializeRootEntry(const std::string& root_id) {
+  DCHECK(root_resource_id_.empty());
+  root_resource_id_ = root_id;
   root_ = CreateDriveDirectory().Pass();
   root_->set_title(kDriveRootDirectory);
   root_->SetBaseNameFromTitle();
@@ -353,7 +355,7 @@ void DriveResourceMetadata::RemoveEntryFromParent(
   DCHECK(!callback.is_null());
 
   // Disallow deletion of root.
-  if (resource_id == kDriveRootDirectoryResourceId) {
+  if (resource_id == root_resource_id_) {
     PostFileMoveCallbackError(callback, DRIVE_FILE_ERROR_ACCESS_DENIED);
     return;
   }
@@ -710,7 +712,7 @@ void DriveResourceMetadata::InitResourceMap(
       } else {
         NOTREACHED() << "Parent is not a directory " << parent->resource_id();
       }
-    } else if (entry->resource_id() == kDriveRootDirectoryResourceId) {
+    } else if (entry->resource_id() == root_resource_id_) {
       root_.reset(entry->AsDriveDirectory());
       DCHECK(root_.get());
       AddEntryToResourceMap(root_.get());