Fix wrong surfaceRequiresRedraw check

We only need to redraw if the size /changed/ not
if it was the same. Also fix damageId to not use
frameNumber as repeated redraws of the same frame
would toggle.

Bug: 143711430
Test: systrace
Change-Id: I8ac4629c9ff4fd51de33d1be7aa46ccc995ba342
diff --git a/libs/hwui/renderthread/CanvasContext.h b/libs/hwui/renderthread/CanvasContext.h
index 6e3e43a..b192d46 100644
--- a/libs/hwui/renderthread/CanvasContext.h
+++ b/libs/hwui/renderthread/CanvasContext.h
@@ -245,6 +245,7 @@
     // Need at least 4 because we do quad buffer. Add a 5th for good measure.
     RingBuffer<SwapHistory, 5> mSwapHistory;
     int64_t mFrameNumber = -1;
+    int64_t mDamageId = 0;
 
     // last vsync for a dropped frame due to stuffed queue
     nsecs_t mLastDropVsync = 0;