Add isEncoded to SkImageGenerator

src/core/SkImageGenerator.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkImageGenerator.h"
 #include "SkNextID.h"
 
@@ skipping 91 matching lines @@
     const SkIRect subset = SkIRect::MakeXYWH(subsetOrigin.x(), subsetOrigin.y(),
                                              subsetPixels.width(), subsetPixels.height());
     if (!SkIRect::MakeWH(scaledSize.width(), scaledSize.height()).contains(subset)) {
         return false;
     }
     return this->onGenerateScaledPixels(scaledSize, subsetOrigin, subsetPixels);
 }
 
 /////////////////////////////////////////////////////////////////////////////////////////////
 
+bool SkImageGenerator::onIsEncoded() const {
+    return false;
+}
+
 SkData* SkImageGenerator::onRefEncodedData(SK_REFENCODEDDATA_CTXPARAM) {
     return nullptr;
 }
 
 bool SkImageGenerator::onGetPixels(const SkImageInfo& info, void* dst, size_t rb,
                                    SkPMColor* colors, int* colorCount) {
     return false;
 }
 
 ///////////////////////////////////////////////////////////////////////////////////////////////////
@@ skipping 88 matching lines @@
     if (nullptr == data) {
         return nullptr;
     }
     if (gFactory) {
         if (SkImageGenerator* generator = gFactory(data)) {
             return generator;
         }
     }
     return SkImageGenerator::NewFromEncodedImpl(data);
 }