Add `SkIRect bounds()` convenience method to SkImageInfo and SkBitmap.

tests/WritePixelsTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBitmapDevice.h"
 #include "SkCanvas.h"
 #include "SkColorPriv.h"
@@ skipping 177 matching lines @@
 static bool check_write(skiatest::Reporter* reporter, SkCanvas* canvas, const SkBitmap& bitmap,
                        int writeX, int writeY) {
     const SkImageInfo canvasInfo = canvas->imageInfo();
     size_t canvasRowBytes;
     const uint32_t* canvasPixels;
 
     // Can't use canvas->peekPixels(), as we are trying to look at GPU pixels sometimes as well.
     // At some point this will be unsupported, as we won't allow accessBitmap() to magically call
     // readPixels for the client.
     SkBitmap secretDevBitmap;
-    canvas->readPixels(SkIRect::MakeWH(canvasInfo.width(), canvasInfo.height()), &secretDevBitmap);
+    canvas->readPixels(canvasInfo.bounds(), &secretDevBitmap);
 
     SkAutoLockPixels alp(secretDevBitmap);
     canvasRowBytes = secretDevBitmap.rowBytes();
     canvasPixels = static_cast<const uint32_t*>(secretDevBitmap.getPixels());
 
     if (NULL == canvasPixels) {
         return false;
     }
 
     if (canvasInfo.width() != DEV_W ||
@@ skipping 262 matching lines @@
                         SkIRect writeRect = SkIRect::MakeXYWH(rect.fLeft, rect.fTop,
                                                               bmp.width(), bmp.height());
                         bool intersects = SkIRect::Intersects(canvasRect, writeRect) ;
                         REPORTER_ASSERT(reporter, intersects == (idBefore != idAfter));
                     }
                 }
             }
         }
     }
 }