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
WebContentsImpl::GetJavaWebContents() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  WebContentsAndroid* web_contents_android =
      static_cast<WebContentsAndroid*>(GetUserData(kWebContentsAndroidKey));
  if (!web_contents_android) {
    web_contents_android = new WebContentsAndroid(this);
    SetUserData(kWebContentsAndroidKey, web_contents_android);
  }
  return web_contents_android->GetJavaObject();
}

WebContentsImpl::GetJavaWebContents() {
  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));

  WebContentsAndroid* web_contents_android =
      static_cast<WebContentsAndroid*>(GetUserData(kWebContentsAndroidKey));
  if (!web_contents_android) {
    web_contents_android = new WebContentsAndroid(this);
    SetUserData(kWebContentsAndroidKey, web_contents_android);
  }
  return web_contents_android->GetJavaObject();
}
