Separate JSON functions from DMWriteTask.

dm/DMJsonWriter.h

Index: dm/DMJsonWriter.h
diff --git a/dm/DMJsonWriter.h b/dm/DMJsonWriter.h
new file mode 100644
index 0000000000000000000000000000000000000000..c358fdd9237285779294489964ade172c11305d1
--- /dev/null
+++ b/dm/DMJsonWriter.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef DMJsonWriter_DEFINED
+#define DMJsonWriter_DEFINED
+
+#include "SkString.h"
+
+namespace DM {
+
+/**
+ *  Class for collecting results from DM and writing to a json file.
+ *  All methods are thread-safe.
+ */
+class JsonWriter {
+public:
+    /**
+     *  Info describing a single run.
+     */
+    struct BitmapResult {
+        SkString name;            // E.g. "ninepatch-stretch", "desk-gws_skp"
+        SkString config;          //      "gpu", "8888"
+        SkString mode;            //      "direct", "default-tilegrid", "pipe"
+        SkString sourceType;      //      "GM", "SKP"
+        SkString md5;             // In ASCII, so 32 bytes long.
+    };
+
+    /**
+     *  Add a result to the end of the list of results.
+     */
+    static void AddBitmapResult(const BitmapResult&);
+
+    /**
+     *  Write all collected results to the file FLAGS_writePath[0]/dm.json.
+     */
+    static void DumpJson();
+};
+
+} // namespace DM
+#endif // DMJsonWriter_DEFINED