Code:  void GDataDirectoryService::InitializeRootEntry(const std::string& root_id) {
  root_.reset(new GDataDirectory(NULL, this));
   root_->set_title(kGDataRootDirectory);
   root_->SetBaseNameFromTitle();
   root_->set_resource_id(root_id);
  AddEntryToResourceMap(root_.get());
}

Commit Message: Remove parent* arg from GDataEntry ctor.

* Remove static FromDocumentEntry from GDataEntry, GDataFile, GDataDirectory. Replace with InitFromDocumentEntry.
* Move common code from GDataFile::InitFromDocumentEntry and GDataDirectory::InitFromDocumentEntry to GDataEntry::InitFromDocumentEntry.
* Add GDataDirectoryService::FromDocumentEntry and use this everywhere.
* Make ctors of GDataFile, GDataDirectory private, so these must be created by GDataDirectoryService's CreateGDataFile and
CreateGDataDirectory. Make GDataEntry ctor protected.

BUG=141494
TEST=unit tests.
Review URL: https://chromiumcodereview.appspot.com/10854083

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@151008 0039d316-1c4b-4281-b951-d872f2087c98
CWE ID: CWE-399
 void GDataDirectoryService::InitializeRootEntry(const std::string& root_id) {
  root_.reset(CreateGDataDirectory());
   root_->set_title(kGDataRootDirectory);
   root_->SetBaseNameFromTitle();
   root_->set_resource_id(root_id);
  AddEntryToResourceMap(root_.get());
}
