add flag to stage SkCanvas virtual change
add flag to stage SkCanvas virtual change

Test: make

Change-Id: Ib87b98cbdc097dae745f2cef9c9b9695eec7a242

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia