Remove SkImageGenerator pieces only for SkCodec.

src/lazy/SkDiscardablePixelRef.cpp

Index: src/lazy/SkDiscardablePixelRef.cpp
diff --git a/src/lazy/SkDiscardablePixelRef.cpp b/src/lazy/SkDiscardablePixelRef.cpp
index 73fa4ce84cc2062e29c9dfb67fdd856229f71156..19bfc8ccc798b84cdbb7829b89d6f4dfe04fbd7d 100644
--- a/src/lazy/SkDiscardablePixelRef.cpp
+++ b/src/lazy/SkDiscardablePixelRef.cpp
@@ -71,18 +71,12 @@ bool SkDiscardablePixelRef::onNewLockPixels(LockRec* rec) {
     SkPMColor colors[256];
     int colorCount = 0;
 
-    const SkImageGenerator::Result result = fGenerator->getPixels(info, pixels, fRowBytes, NULL,
-                                                                  colors, &colorCount);
-    switch (result) {
-        case SkImageGenerator::kSuccess:
-        case SkImageGenerator::kIncompleteInput:
-            break;
-        default:
-            fDiscardableMemory->unlock();
-            fDiscardableMemoryIsLocked = false;
-            SkDELETE(fDiscardableMemory);
-            fDiscardableMemory = NULL;
-            return false;
+    if (!fGenerator->getPixels(info, pixels, fRowBytes, colors, &colorCount)) {
+        fDiscardableMemory->unlock();
+        fDiscardableMemoryIsLocked = false;
+        SkDELETE(fDiscardableMemory);
+        fDiscardableMemory = NULL;
+        return false;
     }
 
     // Note: our ctable is not purgeable, as it is not stored in the discardablememory block.