add SkBitmap::installPixelRef()

BUG=
R=scroggo@google.com

Review URL: https://codereview.chromium.org/129423002

git-svn-id: http://skia.googlecode.com/svn/trunk@13055 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/lazy/SkDiscardablePixelRef.cpp b/src/lazy/SkDiscardablePixelRef.cpp
index abd80f2..eb5c2f9 100644
--- a/src/lazy/SkDiscardablePixelRef.cpp
+++ b/src/lazy/SkDiscardablePixelRef.cpp
@@ -94,6 +94,6 @@
     SkAutoTUnref<SkDiscardablePixelRef> ref(
         SkNEW_ARGS(SkDiscardablePixelRef,
                    (info, autoGenerator.detach(), dst->rowBytes(), factory)));
-    dst->setPixelRef(ref);
+    dst->installPixelRef(ref);
     return true;
 }