Add support for serializing/deserializing of SkDrawable

src/core/SkValidatingReadBuffer.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmap.h"
 #include "SkErrorInternals.h"
 #include "SkValidatingReadBuffer.h"
@@ skipping 228 matching lines @@
     SkFlattenable::Factory factory = SkFlattenable::NameToFactory(cname);
     if (nullptr == factory) {
         return nullptr; // writer failed to give us the flattenable
     }
 
     // if we get here, factory may still be null, but if that is the case, the
     // failure was ours, not the writer.
     SkFlattenable* obj = nullptr;
     uint32_t sizeRecorded = this->readUInt();
     if (factory) {
+        // Check if a custom Factory has been specified for this flattenable.
+        SkFlattenable::Factory* customFactoryPtr = getCustomFactory(factory);
+        if (customFactoryPtr) {
+            factory = *customFactoryPtr;
+        }
+
         size_t offset = fReader.offset();
         obj = (*factory)(*this);
         // check that we read the amount we expected
         size_t sizeRead = fReader.offset() - offset;
         this->validate(sizeRecorded == sizeRead);
         if (fError) {
             // we could try to fix up the offset...
             SkSafeUnref(obj);
             obj = nullptr;
         }
     } else {
         // we must skip the remaining data
         this->skip(sizeRecorded);
         SkASSERT(false);
     }
     return obj;
 }
 
 void SkValidatingReadBuffer::skipFlattenable() {
     SkString name;
     this->readString(&name);
     if (fError) {
         return;
     }
     uint32_t sizeRecorded = this->readUInt();
     this->skip(sizeRecorded);
 }