Merge "Only flush after all layers are drawn instead of after each layer."

void SkiaPipeline::renderLayersImpl(const LayerUpdateQueue& layers,

        bool opaque, bool wideColorGamut) {

    // TODO: Handle wide color gamut

    sk_sp<GrContext> cachedContext;

    // Render all layers that need to be updated, in order.

    for (size_t i = 0; i < layers.entries().size(); i++) {

        RenderNode* layerNode = layers.entries()[i].renderNode.get();

            RenderNodeDrawable root(layerNode, layerCanvas, false);

            root.forceDraw(layerCanvas);

            layerCanvas->restoreToCount(saveCount);

            layerCanvas->flush();

            mLightCenter = savedLightCenter;

            // cache the current context so that we can defer flushing it until

            // either all the layers have been rendered or the context changes

            GrContext* currentContext = layerCanvas->getGrContext();

            if (cachedContext.get() != currentContext) {

                if (cachedContext.get()) {

                    cachedContext->flush();

                }

                cachedContext.reset(SkSafeRef(currentContext));

            }

        }

    }

    if (cachedContext.get()) {

        cachedContext->flush();

    }

}

bool SkiaPipeline::createOrUpdateLayer(RenderNode* node,

        const DamageAccumulator& damageAccumulator, bool wideColorGamut) {

    SkSurface* layer = node->getLayerSurface();