DM: add --serialize

dm/DMWriteTask.cpp

 #include "DMWriteTask.h"
 
 #include "DMUtil.h"
 #include "SkCommandLineFlags.h"
 #include "SkImageEncoder.h"
 
 #include <string.h>
 
 DEFINE_string2(writePath, w, "", "If set, write GMs here as .pngs.");
 
 namespace DM {
 
 WriteTask::WriteTask(const Task& parent, SkBitmap bitmap)
     : Task(parent)
     , fBitmap(bitmap) {
     // Split parent's name <gmName>_<config> into gmName and config.
     const char* parentName = parent.name().c_str();
     const char* fromLastUnderscore = strrchr(parentName, '_');
     const ptrdiff_t gmNameLength = fromLastUnderscore - parentName;
 
     fConfig.set(fromLastUnderscore+1);
     fGmName.set(parentName, gmNameLength);
 }
 
 void WriteTask::draw() {
     const char* root = FLAGS_writePath[0];
     const SkString dir = SkOSPath::SkPathJoin(root, fConfig.c_str());
     if (!sk_mkdir(root) ||
         !sk_mkdir(dir.c_str())  ||
-        !SkImageEncoder::EncodeFile(png(SkOSPath::SkPathJoin(dir.c_str(), fGmName.c_str())).c_str(),
+        !SkImageEncoder::EncodeFile(Png(SkOSPath::SkPathJoin(dir.c_str(), fGmName.c_str())).c_str(),
                                     fBitmap,
                                     SkImageEncoder::kPNG_Type,
                                     100/*quality*/))
     {
         this->fail();
     }
 }
 
 SkString WriteTask::name() const {
     return SkStringPrintf("writing %s/%s.png", fConfig.c_str(), fGmName.c_str());
 }
 
 bool WriteTask::shouldSkip() const {
     return FLAGS_writePath.isEmpty();
 }
 
 }  // namespace DM