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
  RenderViewSizeObserver(Shell* shell, const gfx::Size& wcv_new_size)
      : WebContentsObserver(shell->web_contents()),
        shell_(shell),
        wcv_new_size_(wcv_new_size) {
  }

  RenderViewSizeObserver(Shell* shell, const gfx::Size& wcv_new_size)
      : WebContentsObserver(shell->web_contents()),
        shell_(shell),
        wcv_new_size_(wcv_new_size) {
  }
