Make WebContentsDelegate::OpenColorChooser return NULL on failure

Changing WebContentsDelegate::OpenColorChooser to return NULL on failure so we don't put the same ColorChooser into two scoped_ptrs(WebContentsImpl::color_chooser_)

BUG=331790

Review URL: https://codereview.chromium.org/128053002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244710 0039d316-1c4b-4281-b951-d872f2087c98
BrowserPluginGuest* WebContentsImpl::CreateGuest(
    BrowserContext* browser_context,
    SiteInstance* site_instance,
    int guest_instance_id,
    scoped_ptr<base::DictionaryValue> extra_params) {
  WebContentsImpl* new_contents = new WebContentsImpl(browser_context, NULL);

  BrowserPluginGuest::Create(
      guest_instance_id, site_instance, new_contents, extra_params.Pass());

  WebContents::CreateParams create_params(browser_context, site_instance);
  new_contents->Init(create_params);

  new_contents->is_subframe_ = true;

  return new_contents->browser_plugin_guest_.get();
}

BrowserPluginGuest* WebContentsImpl::CreateGuest(
    BrowserContext* browser_context,
    SiteInstance* site_instance,
    int guest_instance_id,
    scoped_ptr<base::DictionaryValue> extra_params) {
  WebContentsImpl* new_contents = new WebContentsImpl(browser_context, NULL);

  BrowserPluginGuest::Create(
      guest_instance_id, site_instance, new_contents, extra_params.Pass());

  WebContents::CreateParams create_params(browser_context, site_instance);
  new_contents->Init(create_params);

  new_contents->is_subframe_ = true;

  return new_contents->browser_plugin_guest_.get();
}
