Image filters: change applyCropRect() to take a src rect.

src/effects/SkPaintImageFilter.cpp

Index: src/effects/SkPaintImageFilter.cpp
diff --git a/src/effects/SkPaintImageFilter.cpp b/src/effects/SkPaintImageFilter.cpp
index d141f34dfb075d45d2fd05305b07c0e724abf95f..c0210513ac3c65cba731de04625bbe8965d867cd 100644
--- a/src/effects/SkPaintImageFilter.cpp
+++ b/src/effects/SkPaintImageFilter.cpp
@@ -39,7 +39,7 @@ bool SkPaintImageFilter::onFilterImage(Proxy* proxy,
                                             SkBitmap* result,
                                             SkIPoint* offset) const {
     SkIRect bounds;
-    if (!this->applyCropRect(ctx, source, SkIPoint::Make(0, 0), &bounds)) {
+    if (!this->applyCropRect(ctx, source.bounds(), &bounds)) {
         return false;
     }