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

src/core/SkCanvas.cpp

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkCanvasPriv.h"
 #include "SkBitmapDevice.h"
@@ skipping 1242 matching lines @@
     while (iter.next()) {
         paint = &looper.paint();
         SkImageFilter* filter = paint->getImageFilter();
         SkIPoint pos = { x - iter.getX(), y - iter.getY() };
         if (filter && !iter.fDevice->canHandleImageFilter(filter)) {
             SkDeviceImageFilterProxy proxy(iter.fDevice);
             SkBitmap dst;
             SkIPoint offset = SkIPoint::Make(0, 0);
             SkMatrix matrix = *iter.fMatrix;
             matrix.postTranslate(SkIntToScalar(-pos.x()), SkIntToScalar(-pos.y()));
-            SkIRect clipBounds = SkIRect::MakeWH(bitmap.width(), bitmap.height());
+            const SkIRect clipBounds = bitmap.bounds();
             SkAutoTUnref<SkImageFilter::Cache> cache(iter.fDevice->getImageFilterCache());
             SkImageFilter::Context ctx(matrix, clipBounds, cache.get());
             if (filter->filterImage(&proxy, bitmap, ctx, &dst, &offset)) {
                 SkPaint tmpUnfiltered(*paint);
                 tmpUnfiltered.setImageFilter(NULL);
                 iter.fDevice->drawSprite(iter, dst, pos.x() + offset.x(), pos.y() + offset.y(),
                                          tmpUnfiltered);
             }
         } else {
             iter.fDevice->drawSprite(iter, bitmap, pos.x(), pos.y(), *paint);
@@ skipping 1276 matching lines @@
     }
 
     if (matrix) {
         canvas->concat(*matrix);
     }
 }
 
 SkAutoCanvasMatrixPaint::~SkAutoCanvasMatrixPaint() {
     fCanvas->restoreToCount(fSaveCount);
 }