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 a6f780c7c917e6021eb82393fd9134d30e3cd97a..22152b9ddf69eccc6f545cb97cca108012efc474 100644
--- a/chrome/browser/chromeos/drive/drive_resource_metadata.cc
+++ b/chrome/browser/chromeos/drive/drive_resource_metadata.cc
@@ -198,8 +198,8 @@ DriveResourceMetadata::DriveResourceMetadata()
       origin_(UNINITIALIZED),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
   root_ = CreateDriveDirectory().Pass();
-  if (!google_apis::util::IsDriveV2ApiEnabled())
-    InitializeRootEntry(kDriveRootDirectoryResourceId);
+  root_->set_title(kDriveRootDirectory);
+  root_->SetBaseNameFromTitle();
 }
 
 DriveResourceMetadata::~DriveResourceMetadata() {
@@ -232,11 +232,9 @@ scoped_ptr<DriveDirectory> DriveResourceMetadata::CreateDriveDirectory() {
   return scoped_ptr<DriveDirectory>(new DriveDirectory(this));
 }
 
-void DriveResourceMetadata::InitializeRootEntry(const std::string& root_id) {
-  root_ = CreateDriveDirectory().Pass();
-  root_->set_title(kDriveRootDirectory);
-  root_->SetBaseNameFromTitle();
-  root_->set_resource_id(root_id);
+void DriveResourceMetadata::SetRootResourceId(const std::string& id) {
+  DCHECK(root_->resource_id().empty());
+  root_->set_resource_id(id);
   AddEntryToResourceMap(root_.get());
 }
 
@@ -244,10 +242,13 @@ void DriveResourceMetadata::ClearRoot() {
   if (!root_.get())
     return;
 
-  // Note that children have a reference to root_,
-  // so we need to delete them here.
-  root_->RemoveChildren();
-  RemoveEntryFromResourceMap(root_->resource_id());
+  // If root resource ID is not set, it means no children.
+  if (!root_->resource_id().empty()) {
+    // Note that children have a reference to root_,
+    // so we need to delete them here.
+    root_->RemoveChildren();
+    RemoveEntryFromResourceMap(root_->resource_id());
+  }
   DCHECK(resource_map_.empty());
   resource_map_.clear();
   root_.reset();
@@ -365,7 +366,7 @@ 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;
   }
@@ -652,7 +653,6 @@ 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()) {
@@ -661,6 +661,8 @@ void DriveResourceMetadata::InitResourceMap(
     return;
   }
 
+  // Save root directory resource ID as ClearRoot() resets |root_|.
+  std::string saved_root_resource_id = root_->resource_id();
   ClearRoot();
 
   // Version check.
@@ -722,7 +724,7 @@ 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());
@@ -808,6 +810,8 @@ bool DriveResourceMetadata::ParseFromString(
   }
 
   root_->FromProto(proto.drive_directory());
+  // Root resource ID is already set from proto.
+  AddEntryToResourceMap(root_.get());
 
   origin_ = FROM_CACHE;
   largest_changestamp_ = proto.largest_changestamp();