Qualify the return value of SkImageDecoder::decode

src/images/SkImageDecoder.cpp

Index: src/images/SkImageDecoder.cpp
diff --git a/src/images/SkImageDecoder.cpp b/src/images/SkImageDecoder.cpp
index f9b04e39a7b3de3b247221a13426ef663c42c647..2d41e9346f5a39cab112085e5cc2766cfdcf7a52 100644
--- a/src/images/SkImageDecoder.cpp
+++ b/src/images/SkImageDecoder.cpp
@@ -156,7 +156,8 @@ SkColorType SkImageDecoder::getPrefColorType(SrcDepth srcDepth, bool srcHasAlpha
     return ct;
 }
 
-bool SkImageDecoder::decode(SkStream* stream, SkBitmap* bm, SkColorType pref, Mode mode) {
+SkImageDecoder::Result SkImageDecoder::decode(SkStream* stream, SkBitmap* bm, SkColorType pref,
+                                              Mode mode) {
     // we reset this to false before calling onDecode
     fShouldCancelDecode = false;
     // assign this, for use by getPrefColorType(), in case fUsePrefTable is false
@@ -164,12 +165,12 @@ bool SkImageDecoder::decode(SkStream* stream, SkBitmap* bm, SkColorType pref, Mo
 
     // pass a temporary bitmap, so that if we return false, we are assured of
     // leaving the caller's bitmap untouched.
-    SkBitmap    tmp;
-    if (!this->onDecode(stream, &tmp, mode)) {
-        return false;
+    SkBitmap tmp;
+    const Result result = this->onDecode(stream, &tmp, mode);
+    if (kFailure != result) {
+        bm->swap(tmp);
     }
-    bm->swap(tmp);
-    return true;
+    return result;
 }
 
 bool SkImageDecoder::decodeSubset(SkBitmap* bm, const SkIRect& rect, SkColorType pref) {