RendererWebColorChooserImpl shouldn't be destroyed by RenderViewObserver::OnDestruct

RenderWebColorChooserImpl is owned by blink::ColorChooserUIController so it should not be destroyed in RenderViewObserver::OnDestruct

BUG=342735

Review URL: https://codereview.chromium.org/181233006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255276 0039d316-1c4b-4281-b951-d872f2087c98