Avoid caching resources for volatile bitmap shaders

src/core/SkBitmapProvider.cpp

Index: src/core/SkBitmapProvider.cpp
diff --git a/src/core/SkBitmapProvider.cpp b/src/core/SkBitmapProvider.cpp
index dd34fb04abce726e85ed873815c209040287d9aa..37f8dc9d52e9de111634ce18eab0426cc47a6692 100644
--- a/src/core/SkBitmapProvider.cpp
+++ b/src/core/SkBitmapProvider.cpp
@@ -49,7 +49,9 @@ SkImageInfo SkBitmapProvider::info() const {
 
 bool SkBitmapProvider::isVolatile() const {
     if (fImage) {
-        return false;   // add flag to images?
+        // add flag to images?
+        const SkBitmap* bm = as_IB(fImage)->onPeekBitmap();
+        return bm ? bm->isVolatile() : false;
     } else {
         return fBitmap.isVolatile();
     }