Remove SkImageGenerator pieces only for SkCodec.

src/lazy/SkCachingPixelRef.cpp

Index: src/lazy/SkCachingPixelRef.cpp
diff --git a/src/lazy/SkCachingPixelRef.cpp b/src/lazy/SkCachingPixelRef.cpp
index 5fc0d2a87fa7180e88ed3404c175ee0750cf2f5e..3edd0de4fb3df8125faaef69434294babed1bf17 100644
--- a/src/lazy/SkCachingPixelRef.cpp
+++ b/src/lazy/SkCachingPixelRef.cpp
@@ -53,15 +53,9 @@ bool SkCachingPixelRef::onNewLockPixels(LockRec* rec) {
             fErrorInDecoding = true;
             return false;
         }
-        const SkImageGenerator::Result result = fImageGenerator->getPixels(info,
-                fLockedBitmap.getPixels(), fRowBytes);
-        switch (result) {
-            case SkImageGenerator::kIncompleteInput:
-            case SkImageGenerator::kSuccess:
-                break;
-            default:
-                fErrorInDecoding = true;
-                return false;
+        if (!fImageGenerator->getPixels(info, fLockedBitmap.getPixels(), fRowBytes)) {
+            fErrorInDecoding = true;
+            return false;
         }
         fLockedBitmap.setImmutable();
         SkBitmapCache::Add(this, info.bounds(), fLockedBitmap);