add src-rect-constraint to drawImageRect

Follow-on work
- unify around SrcRectConstraint (i.e. drawBitmapRect)
- remove silly drawBitmapRectToRect alias
- clean-up (possibly remove) alias problems around drawBitmapRect + IRect parameter

BUG=skia:

Review URL: https://codereview.chromium.org/1228083004
diff --git a/src/utils/SkNWayCanvas.cpp b/src/utils/SkNWayCanvas.cpp
index 8ae8422..706c769 100644
--- a/src/utils/SkNWayCanvas.cpp
+++ b/src/utils/SkNWayCanvas.cpp
@@ -170,8 +170,7 @@
     }
 }
 
-void SkNWayCanvas::onDrawDRRect(const SkRRect& outer, const SkRRect& inner,
-                                const SkPaint& paint) {
+void SkNWayCanvas::onDrawDRRect(const SkRRect& outer, const SkRRect& inner, const SkPaint& paint) {
     Iter iter(fList);
     while (iter.next()) {
         iter->drawDRRect(outer, inner, paint);
@@ -194,10 +193,10 @@
 }
 
 void SkNWayCanvas::onDrawBitmapRect(const SkBitmap& bitmap, const SkRect* src, const SkRect& dst,
-                                    const SkPaint* paint, DrawBitmapRectFlags flags) {
+                                    const SkPaint* paint, SK_VIRTUAL_CONSTRAINT_TYPE constraint) {
     Iter iter(fList);
     while (iter.next()) {
-        iter->drawBitmapRectToRect(bitmap, src, dst, paint, flags);
+        iter->drawBitmapRect(bitmap, src, dst, paint, (SrcRectConstraint)constraint);
     }
 }
 
@@ -218,10 +217,10 @@
 }
 
 void SkNWayCanvas::onDrawImageRect(const SkImage* image, const SkRect* src, const SkRect& dst,
-                                   const SkPaint* paint) {
+                                   const SkPaint* paint SRC_RECT_CONSTRAINT_PARAM(constraint)) {
     Iter iter(fList);
     while (iter.next()) {
-        iter->drawImageRect(image, src, dst, paint);
+        iter->drawImageRect(image, src, dst, paint SRC_RECT_CONSTRAINT_ARG(constraint));
     }
 }