public boolean waitForSplashImageFile(int timeoutMillis) {
        try {
            return mFileReceivingLatch.await(timeoutMillis, TimeUnit.MILLISECONDS);
        } catch (InterruptedException e) {
            return false;
        }
    }
Waits until a splash image file is successfully received and decoded in {@link #receiveFile}.
Returns whether that happened before timeout.
If already received, returns "true" immediately.
customtabs/tests/src/android/support/customtabs/TestCustomTabsService.java