Add matrix constructing helpers to SkMatrix

gm/multipicturedraw.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 "gm.h"
 
 #include "SkColorFilter.h"
@@ skipping 405 matching lines @@
             step.fX = SkIntToScalar(x*kTileWidth);
             step.fY = SkIntToScalar(y*kTileHeight);
             step.fPaint = SkNEW(SkPaint);
             step.fPaint->setColorFilter(
                 SkColorFilter::CreateModeFilter(colors[x][y], SkXfermode::kModulate_Mode))->unref();
 
             step.fSurf = create_compat_surface(finalCanvas, kTileWidth, kTileHeight);
 
             SkCanvas* subCanvas = step.fSurf->getCanvas();
 
-            SkMatrix trans;
-            trans.setTranslate(-SkIntToScalar(x*kTileWidth), -SkIntToScalar(y*kTileHeight));
+            const SkMatrix trans = SkMatrix::MakeTrans(-SkIntToScalar(x*kTileWidth), 
+                                                       -SkIntToScalar(y*kTileHeight));
 
             create_content(mpd, pfGen, pictures, subCanvas, trans);
         }
     }
 }
 
 static const PFLayoutMtd gLayoutMthds[] = { simple, tiled };
 
 namespace skiagm {
     /**
@@ skipping 125 matching lines @@
                                                 MultiPictureDraw::kTiled_Layout));)
     DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::kPathClipMulti_Content,
                                                 MultiPictureDraw::kTiled_Layout));)
     DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::kInvPathClipMulti_Content,
                                                 MultiPictureDraw::kTiled_Layout));)
     DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::kSierpinski_Content,
                                                 MultiPictureDraw::kTiled_Layout));)
     DEF_GM(return SkNEW_ARGS(MultiPictureDraw, (MultiPictureDraw::kBigLayer_Content,
                                                 MultiPictureDraw::kTiled_Layout));)
 }