Code: GDataDirectoryService::GDataDirectoryService()
    : blocking_task_runner_(NULL),
      serialized_size_(0),
       largest_changestamp_(0),
       origin_(UNINITIALIZED),
       weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
  root_.reset(new GDataDirectory(NULL, this));
   if (!util::IsDriveV2ApiEnabled())
     InitializeRootEntry(kGDataRootDirectoryResourceId);
 }

Vulnerability Type: DoS 
CWE ID: CWE-399
Summary: Use-after-free vulnerability in Google Chrome before 24.0.1312.56 allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors related to the handling of fonts in CANVAS elements.
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