remove getter for imagegenerator factory, update test

BUG=skia:

Review URL: https://codereview.chromium.org/1223413002

2 files changed, 7 insertions, 2 deletions

diff --git a/include/core/SkGraphics.h b/include/core/SkGraphics.h
index e552633d5f..f2e3d8dac0 100644
--- a/include/core/SkGraphics.h
+++ b/include/core/SkGraphics.h
@@ -150,9 +150,11 @@ public:
      *  To instantiate images from encoded data, first looks at this runtime function-ptr. If it
      *  exists, it is called to create an SkImageGenerator from SkData. If there is no function-ptr
      *  or there is, but it returns NULL, then skia will call its internal default implementation.
+     *
+     *  Returns the previous factory (which could be NULL).
      */
-    static ImageGeneratorFromEncodedFactory GetImageGeneratorFromEncodedFactory();
-    static void SetImageGeneratorFromEncodedFactory(ImageGeneratorFromEncodedFactory);
+    static ImageGeneratorFromEncodedFactory
+           SetImageGeneratorFromEncodedFactory(ImageGeneratorFromEncodedFactory);
 };
 
 class SkAutoGraphics {
diff --git a/include/core/SkImageGenerator.h b/include/core/SkImageGenerator.h
index 46001c8537..c133476d5b 100644
--- a/include/core/SkImageGenerator.h
+++ b/include/core/SkImageGenerator.h
@@ -221,6 +221,9 @@ protected:
 private:
     const SkImageInfo fInfo;
 
+    // This is our default impl, which may be different on different platforms.
+    // It is called from NewFromEncoded() after it has checked for any runtime factory.
+    // The SkData will never be NULL, as that will have been checked by NewFromEncoded.
     static SkImageGenerator* NewFromEncodedImpl(SkData*);
 };