DM: add --serialize

dm/DMSerializeTask.h

+#ifndef DMSerializeTask_DEFINED
+#define DMSerializeTask_DEFINED
+
+#include "DMTask.h"
+#include "SkBitmap.h"
+#include "SkString.h"
+#include "SkTemplates.h"
+#include "gm.h"
+
+// Record a picture, serialize it, deserialize it, then draw it and compare to reference bitmap.
+
+namespace DM {
+
+class SerializeTask : public Task {
+
+public:
+    SerializeTask(const Task& parent,
+                  skiagm::GM*,
+                  SkBitmap reference);
+
+    virtual void draw() SK_OVERRIDE;
+    virtual bool usesGpu() const SK_OVERRIDE { return false; }
+    virtual bool shouldSkip() const SK_OVERRIDE;
+    virtual SkString name() const SK_OVERRIDE { return fName; }
+
+private:
+    const SkString fName;
+    SkAutoTDelete<skiagm::GM> fGM;
+    const SkBitmap fReference;
+};
+
+}  // namespace DM
+
+#endif  // DMSerializeTask_DEFINED