Maintain a map of all resources in the resource tracker and clear instance back pointers when needed,

BUG=85808
Review URL: http://codereview.chromium.org/7196001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@89746 0039d316-1c4b-4281-b951-d872f2087c98
void Resource::LastPluginRefWasDeleted(bool instance_destroyed) {
void Resource::LastPluginRefWasDeleted() {
   DCHECK(resource_id_ != 0);
   instance()->module()->GetCallbackTracker()->PostAbortForResource(
       resource_id_);
   resource_id_ = 0;
 }

void Resource::LastPluginRefWasDeleted(bool instance_destroyed) {
   DCHECK(resource_id_ != 0);
   instance()->module()->GetCallbackTracker()->PostAbortForResource(
       resource_id_);
   resource_id_ = 0;
  if (instance_destroyed)
    instance_ = NULL;
 }
