DM: add --tileGrid

dm/DMTileGridTask.h

+#ifndef DMTileGridTask_DEFINED
+#define DMTileGridTask_DEFINED
+
+#include "DMTask.h"
+#include "SkBitmap.h"
+#include "SkString.h"
+#include "SkTemplates.h"
+#include "gm.h"
+
+// Records a GM through an SkPicture, draws it in tiles, and compares against the reference bitmap.
+
+namespace DM {
+
+class TileGridTask : public Task {
+
+public:
+    TileGridTask(const Task& parent,  // TileGridTask must be a child task.  Pass its parent here.
+                 skiagm::GM*,         // GM to run through a picture.  Takes ownership.
+                 SkBitmap reference,  // Bitmap to compare picture replay results to.
+                 SkISize tileSize);   // Tile size to use.
+
+    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;
+    const SkISize fTileSize;
+};
+
+}  // namespace DM
+
+#endif  // DMReplayTask_DEFINED