Query the new DisplayCapability for DISPLAY_DECORATION

This allows clients (i.e. SystemUi) to know whether to use
Composition.DISPLAY_DECORATION.

Bug: 193170859
Test: manual
Test: TODO (b/212697197)

Change-Id: I0d3e93bb04937f81e95ef77d196b861621bbdc8d
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index e1b52c5..2d1f9ba 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -594,6 +594,8 @@
     status_t notifyPowerBoost(int32_t boostId) override;
     status_t setGlobalShadowSettings(const half4& ambientColor, const half4& spotColor,
                                      float lightPosY, float lightPosZ, float lightRadius) override;
+    status_t getDisplayDecorationSupport(const sp<IBinder>& displayToken,
+                                         bool* outSupport) const override;
     status_t setFrameRate(const sp<IGraphicBufferProducer>& surface, float frameRate,
                           int8_t compatibility, int8_t changeFrameRateStrategy) override;