Add matrix constructing helpers to SkMatrix

bench/SKPBench.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SKPBench.h"
 #include "SkCommandLineFlags.h"
 #include "SkMultiPictureDraw.h"
@@ skipping 98 matching lines @@
 
             mpd.draw();
 
             for (int j = 0; j < fTileRects.count(); ++j) {
                 fSurfaces[j]->getCanvas()->flush();
             }
         }
     } else {
         for (int i = 0; i < loops; i++) {
             for (int j = 0; j < fTileRects.count(); ++j) {
-                SkMatrix trans;
-                trans.setTranslate(-fTileRects[j].fLeft / fScale,
-                                   -fTileRects[j].fTop / fScale);
+                const SkMatrix trans = SkMatrix::MakeTrans(-fTileRects[j].fLeft / fScale,
+                                                           -fTileRects[j].fTop / fScale);
                 fSurfaces[j]->getCanvas()->drawPicture(fPic, &trans, NULL);
             }
 
             for (int j = 0; j < fTileRects.count(); ++j) {
                 fSurfaces[j]->getCanvas()->flush();
             }
         }
     }
 }