mark bitmaps as immutable as we deserialize them into picture-playback
Review URL: https://codereview.appspot.com/6900045

git-svn-id: http://skia.googlecode.com/svn/trunk@6703 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkPicturePlayback.cpp b/src/core/SkPicturePlayback.cpp
index b1b5112..d0a29d3 100644
--- a/src/core/SkPicturePlayback.cpp
+++ b/src/core/SkPicturePlayback.cpp
@@ -505,7 +505,9 @@
         case PICT_BITMAP_BUFFER_TAG: {
             fBitmaps = SkTRefArray<SkBitmap>::Create(size);
             for (size_t i = 0; i < size; ++i) {
-                buffer.readBitmap(&fBitmaps->writableAt(i));
+                SkBitmap* bm = &fBitmaps->writableAt(i);
+                buffer.readBitmap(bm);
+                bm->setImmutable();
             }
         } break;
         case PICT_MATRIX_BUFFER_TAG: