Delete unneeded pending entries in DidFailProvisionalLoad to prevent a spoof.

BUG=280512
BUG=278899
TEST=See bug for repro steps.

Review URL: https://chromiumcodereview.appspot.com/23978003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@222146 0039d316-1c4b-4281-b951-d872f2087c98
void NavigationControllerImpl::ClearAllScreenshots() {
  screenshot_manager_->ClearAllScreenshots();
}

void NavigationControllerImpl::ClearAllScreenshots() {
  screenshot_manager_->ClearAllScreenshots();
}
