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

src/lazy/SkCachingPixelRef.cpp

Index: src/lazy/SkCachingPixelRef.cpp
diff --git a/src/lazy/SkCachingPixelRef.cpp b/src/lazy/SkCachingPixelRef.cpp
index 1459567e0b4a3e3c1dae4c94cc49c0bb12846869..5ab96562ec8184f9adb1671ea36ec1db54e31829 100644
--- a/src/lazy/SkCachingPixelRef.cpp
+++ b/src/lazy/SkCachingPixelRef.cpp
@@ -45,9 +45,8 @@ bool SkCachingPixelRef::onNewLockPixels(LockRec* rec) {
     }
 
     const SkImageInfo& info = this->info();
-    if (!SkBitmapCache::Find(this->getGenerationID(),
-                             SkIRect::MakeWH(info.width(), info.height()),
-                             &fLockedBitmap)) {
+    if (!SkBitmapCache::Find(
+                this->getGenerationID(), info.bounds(), &fLockedBitmap)) {
         // Cache has been purged, must re-decode.
         if (!fLockedBitmap.tryAllocPixels(info, fRowBytes)) {
             fErrorInDecoding = true;
@@ -58,9 +57,8 @@ bool SkCachingPixelRef::onNewLockPixels(LockRec* rec) {
             return false;
         }
         fLockedBitmap.setImmutable();
-        SkBitmapCache::Add(this->getGenerationID(),
-                           SkIRect::MakeWH(info.width(), info.height()),
-                           fLockedBitmap);
+        SkBitmapCache::Add(
+                this->getGenerationID(), info.bounds(), fLockedBitmap);
     }
 
     // Now bitmap should contain a concrete PixelRef of the decoded image.