Reland r286968: The CL borrows ShareDialog from Files.app and add it to Gallery.

Previous Review URL: https://codereview.chromium.org/431293002

BUG=374667
TEST=manually
R=yoshiki@chromium.org, mtomasz@chromium.org

Review URL: https://codereview.chromium.org/433733004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286975 0039d316-1c4b-4281-b951-d872f2087c98
void FileBrowserPrivateRequestAccessTokenFunction::OnAccessTokenFetched(
    google_apis::GDataErrorCode code,
    const std::string& access_token) {
  SetResult(new base::StringValue(access_token));
  SendResponse(true);
}

void FileBrowserPrivateRequestAccessTokenFunction::OnAccessTokenFetched(
    google_apis::GDataErrorCode code,
    const std::string& access_token) {
  SetResult(new base::StringValue(access_token));
  SendResponse(true);
}
