Add --matrix to DM, to play around with and maybe use on a bot.

dm/DMUtil.cpp

 #include "DMUtil.h"
 
 #include "SkColorPriv.h"
+#include "SkCommandLineFlags.h"
 #include "SkPicture.h"
 #include "SkPictureRecorder.h"
 
+DEFINE_string(matrix, "1 0 0 0 1 0 0 0 1",
+              "Matrix to apply to the canvas before drawing.");
+
 namespace DM {
 
+void CanvasPreflight(SkCanvas* canvas) {
+    if (FLAGS_matrix.count() == 9) {
+        SkMatrix m;
+        for (int i = 0; i < 9; i++) {
+            m[i] = (SkScalar)atof(FLAGS_matrix[i]);
+        }
+        canvas->concat(m);
+    }
+}
+
 SkString UnderJoin(const char* a, const char* b) {
     SkString s;
     s.appendf("%s_%s", a, b);
     return s;
 }
 
 SkString FileToTaskName(SkString filename) {
     for (size_t i = 0; i < filename.size(); i++) {
         if ('_' == filename[i]) { filename[i] = '-'; }
         if ('.' == filename[i]) { filename[i] = '_'; }
     }
     return filename;
 }
 
 SkPicture* RecordPicture(skiagm::GM* gm, SkBBHFactory* factory, bool skr) {
     const SkScalar w = SkIntToScalar(gm->getISize().width()),
                    h = SkIntToScalar(gm->getISize().height());
     SkPictureRecorder recorder;
 
     SkCanvas* canvas = skr ? recorder.EXPERIMENTAL_beginRecording(w, h, factory)
                            : recorder.  DEPRECATED_beginRecording(w, h, factory);
+    CanvasPreflight(canvas);
     canvas->concat(gm->getInitialTransform());
     gm->draw(canvas);
     canvas->flush();
     return recorder.endRecording();
 }
 
 void AllocatePixels(SkColorType ct, int width, int height, SkBitmap* bitmap) {
     bitmap->allocPixels(SkImageInfo::Make(width, height, ct, kPremul_SkAlphaType));
     bitmap->eraseColor(0x00000000);
 }
@@ skipping 55 matching lines @@
 
 bool BitmapsEqual(const SkBitmap& a, const SkBitmap& b) {
     if (a.info() != b.info()) {
         return false;
     }
     const SkAutoLockPixels lockA(a), lockB(b);
     return 0 == memcmp(a.getPixels(), b.getPixels(), a.getSize());
 }
 
 }  // namespace DM