Code: void PPB_URLLoader_Impl::RunCallback(int32_t result) {
  if (!pending_callback_.get()) {
     CHECK(main_document_loader_);
     return;
   }
   TrackedCallback::ClearAndRun(&pending_callback_, result);
 }

Vulnerability Type: DoS Overflow 
CWE ID: CWE-119
Summary: Google Chrome before 21.0.1180.89 does not properly load URLs, which allows remote attackers to cause a denial of service or possibly have unspecified other impact via vectors that trigger a *stale buffer.*
Commit Message: Remove possibility of stale user_buffer_ member in PPB_URLLoader_Impl when FinishedLoading() is called.

BUG=137778

Review URL: https://chromiumcodereview.appspot.com/10797037

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@147914 0039d316-1c4b-4281-b951-d872f2087c98