public boolean serviceExistsForScope(Uri scope, String origin) {
        // If we have an existing connection, we can deal with the scope.
        if (mConnections.get(scope) != null) return true;

        return createServiceIntent(mContext, scope, origin, false) != null;
    }
Checks if a TrustedWebActivityService exists to handle requests for the given scope and
origin. The value will be the same as that returned from {@link #execute} so calling that
and checking the return may be more convenient.

This method should be called on the UI thread.

@param scope The scope used in an Intent to find packages that may have a
             {@link TrustedWebActivityService}.
@param origin An origin that the {@link TrustedWebActivityService} package must be registered
              to.
@return Whether a {@link TrustedWebActivityService} was found.
customtabs/src/android/support/customtabs/trusted/TrustedWebActivityServiceConnectionManager.java