Merge "CanvasContext::draw: flushAndSubmit when not drawing" into sc-dev am: 1171be08

    if (dirty.isEmpty() && Properties::skipEmptyFrames && !surfaceRequiresRedraw()) {

        mCurrentFrameInfo->addFlag(FrameInfoFlags::SkippedFrame);

        if (auto grContext = getGrContext()) {

            // Submit to ensure that any texture uploads complete and Skia can

            // free its staging buffers.

            grContext->flushAndSubmit();

        }

        // Notify the callbacks, even if there's nothing to draw so they aren't waiting

        // indefinitely

        waitOnFences();