Stop copying VectorDrawable pixels when drawing.

Drawing a mutable SkBitmap to an SkCanvas will result in the pixels
being copied and a new genID assigned. This results in both a cpu
and gpu copy every time a VectorDrawable is redrawn.

The solution is to create an SkImage using the flag to instruct it
not to copy the pixels which is what Bitmap::makeImage() does.

Bug: 173732636
Test: captured SKP and verified the genID is consistent between frames
Change-Id: Ie13385e89de51c6b9ee2f2ba31eccbfdf3adac48
diff --git a/libs/hwui/VectorDrawable.cpp b/libs/hwui/VectorDrawable.cpp
index cd908354..6030c36 100644
--- a/libs/hwui/VectorDrawable.cpp
+++ b/libs/hwui/VectorDrawable.cpp
@@ -505,13 +505,11 @@
     SkPaint paint = inPaint;
     paint.setAlpha(mProperties.getRootAlpha() * 255);
 
-    Bitmap& bitmap = getBitmapUpdateIfDirty();
-    SkBitmap skiaBitmap;
-    bitmap.getSkBitmap(&skiaBitmap);
+    sk_sp<SkImage> cachedBitmap = getBitmapUpdateIfDirty().makeImage();
 
     int scaledWidth = SkScalarCeilToInt(mProperties.getScaledWidth());
     int scaledHeight = SkScalarCeilToInt(mProperties.getScaledHeight());
-    canvas->drawBitmapRect(skiaBitmap, SkRect::MakeWH(scaledWidth, scaledHeight), bounds,
+    canvas->drawImageRect(cachedBitmap, SkRect::MakeWH(scaledWidth, scaledHeight), bounds,
                            &paint, SkCanvas::kFast_SrcRectConstraint);
 }