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 4587bf1dd67d48c7f01648ed5c31e89b5b11064c..7581569e9901df2000fb2393aed382b4cf656320 100644
--- a/chrome/browser/chromeos/drive/drive_resource_metadata.cc
+++ b/chrome/browser/chromeos/drive/drive_resource_metadata.cc
@@ -185,9 +185,6 @@ DriveResourceMetadata::DriveResourceMetadata()
       largest_changestamp_(0),
       origin_(UNINITIALIZED),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
-  root_ = CreateDriveDirectory().Pass();
-  if (!google_apis::util::IsDriveV2ApiEnabled())
-    InitializeRootEntry(kDriveRootDirectoryResourceId);
 }
 
 DriveResourceMetadata::~DriveResourceMetadata() {
@@ -221,6 +218,7 @@ scoped_ptr<DriveDirectory> DriveResourceMetadata::CreateDriveDirectory() {
 }
 
 void DriveResourceMetadata::InitializeRootEntry(const std::string& root_id) {
+  DCHECK(!root_.get());
   root_ = CreateDriveDirectory().Pass();
   root_->set_title(kDriveRootDirectory);
   root_->SetBaseNameFromTitle();
@@ -353,7 +351,7 @@ 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;
   }
@@ -611,6 +609,7 @@ void DriveResourceMetadata::InitFromDB(
   DCHECK(!db_path.empty());
   DCHECK(blocking_task_runner);
   DCHECK(!callback.is_null());
+  DCHECK(!root_->resource_id().empty());
 
   if (resource_metadata_db_.get()) {
     callback.Run(DRIVE_FILE_ERROR_IN_USE);
@@ -641,7 +640,6 @@ void DriveResourceMetadata::InitResourceMap(
   DCHECK(!resource_metadata_db_.get());
   DCHECK(!callback.is_null());
 
-
   SerializedMap* serialized_resources = &create_params->serialized_resources;
   resource_metadata_db_ = create_params->db.Pass();
   if (serialized_resources->empty()) {
@@ -650,6 +648,7 @@ void DriveResourceMetadata::InitResourceMap(
     return;
   }
 
+  std::string saved_root_resource_id = root_->resource_id();
   ClearRoot();
 
   // Version check.
@@ -710,7 +709,7 @@ void DriveResourceMetadata::InitResourceMap(
       } else {
         NOTREACHED() << "Parent is not a directory " << parent->resource_id();
       }
-    } else if (entry->resource_id() == kDriveRootDirectoryResourceId) {
+    } else if (entry->resource_id() == saved_root_resource_id) {
       root_.reset(entry->AsDriveDirectory());
       DCHECK(root_.get());
       AddEntryToResourceMap(root_.get());
@@ -772,6 +771,10 @@ void DriveResourceMetadata::SaveToDB() {
                  serialized_resources));
 }
 
+const std::string DriveResourceMetadata::root_resource_id() const {
+  return root_.get() ? root_->resource_id() : std::string();
+}
+
 void DriveResourceMetadata::SerializeToString(
     std::string* serialized_proto) const {
   DriveRootDirectoryProto proto;