Refactor pin/unpinImages to work across pipelines.

Test: existing CTS tests still pass
Change-Id: Ib2607e9853396bad42f298829b5c5da0d210af32
diff --git a/libs/hwui/pipeline/skia/SkiaPipeline.h b/libs/hwui/pipeline/skia/SkiaPipeline.h
index 160046a..877a353 100644
--- a/libs/hwui/pipeline/skia/SkiaPipeline.h
+++ b/libs/hwui/pipeline/skia/SkiaPipeline.h
@@ -34,6 +34,10 @@
 
     void onDestroyHardwareResources() override;
 
+    bool pinImages(std::vector<SkImage*>& mutableImages) override;
+    bool pinImages(LsaVector<sk_sp<Bitmap>>& images) override { return false; }
+    void unpinImages() override;
+
     void renderLayers(const FrameBuilder::LightGeometry& lightGeometry,
             LayerUpdateQueue* layerUpdateQueue, bool opaque,
             const BakedOpRenderer::LightInfo& lightInfo) override;
@@ -101,6 +105,7 @@
 
 private:
     TaskManager mTaskManager;
+    std::vector<sk_sp<SkImage>> mPinnedImages;
     static float mLightRadius;
     static uint8_t mAmbientShadowAlpha;
     static uint8_t mSpotShadowAlpha;