Implement cc::FilterOperations::MapRect.

cc/output/filter_operations.h

Index: cc/output/filter_operations.h
diff --git a/cc/output/filter_operations.h b/cc/output/filter_operations.h
index 13926b5b841a9ad1c11f96027e6a9f3a35ccc9ed..92ac7d45e989b3ff18def686351e0515754dc78a 100644
--- a/cc/output/filter_operations.h
+++ b/cc/output/filter_operations.h
@@ -20,6 +20,10 @@ class TracedValue;
 class Value;
 }
 
+namespace gfx {
+class Rect;
+}
+
 namespace cc {
 
 // An ordered list of filter operations.
@@ -46,6 +50,10 @@ class CC_EXPORT FilterOperations {
 
   bool IsEmpty() const;
 
+  // Maps "forward" to determine which pixels in a destination rect are affected
+  // by pixels in the source rect.
+  gfx::Rect MapRect(const gfx::Rect& rect) const;
+
   void GetOutsets(int* top, int* right, int* bottom, int* left) const;
   bool HasFilterThatMovesPixels() const;
   bool HasFilterThatAffectsOpacity() const;