SurfaceFlinger: plumb composer 2.4 onSeamlessPossible

Plumb onSeamlessPossible callback to SurfaceFlinger.

Test: rev up composer to 2.4
Bug: 141329414
Change-Id: I2166b8ea066002c76781aacbcc985f85f7c255a8
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer.cpp b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
index 0a7009b..1960f43 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer.cpp
+++ b/services/surfaceflinger/DisplayHardware/HWComposer.cpp
@@ -125,6 +125,11 @@
         return android::hardware::Void();
     }
 
+    android::hardware::Return<void> onSeamlessPossible(android::Hwc2::Display display) override {
+        mCallback->onSeamlessPossible(mSequenceId, display);
+        return android::hardware::Void();
+    }
+
 private:
     HWC2::ComposerCallback* mCallback;
     const int32_t mSequenceId;