[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/base/region.h

Index: cc/base/region.h
diff --git a/cc/base/region.h b/cc/base/region.h
index 26c1d2b19900a9280af6159bfd85e997321d9ac7..f3f5cb87ddb0554b2965f08101d90456d0df0407 100644
--- a/cc/base/region.h
+++ b/cc/base/region.h
@@ -24,10 +24,10 @@ class CC_EXPORT Region {
  public:
   Region();
   Region(const Region& region);
-  Region(gfx::Rect rect);  // NOLINT(runtime/explicit)
+  Region(const gfx::Rect& rect);  // NOLINT(runtime/explicit)
   ~Region();
 
-  const Region& operator=(gfx::Rect rect);
+  const Region& operator=(const gfx::Rect& rect);
   const Region& operator=(const Region& region);
 
   void Swap(Region* region);
@@ -36,17 +36,17 @@ class CC_EXPORT Region {
   int GetRegionComplexity() const;
 
   bool Contains(gfx::Point point) const;
-  bool Contains(gfx::Rect rect) const;
+  bool Contains(const gfx::Rect& rect) const;
   bool Contains(const Region& region) const;
 
-  bool Intersects(gfx::Rect rect) const;
+  bool Intersects(const gfx::Rect& rect) const;
   bool Intersects(const Region& region) const;
 
-  void Subtract(gfx::Rect rect);
+  void Subtract(const gfx::Rect& rect);
   void Subtract(const Region& region);
-  void Union(gfx::Rect rect);
+  void Union(const gfx::Rect& rect);
   void Union(const Region& region);
-  void Intersect(gfx::Rect rect);
+  void Intersect(const gfx::Rect& rect);
   void Intersect(const Region& region);
 
   bool Equals(const Region& other) const {
@@ -100,7 +100,7 @@ inline Region SubtractRegions(const Region& a, const Region& b) {
   return result;
 }
 
-inline Region SubtractRegions(const Region& a, gfx::Rect b) {
+inline Region SubtractRegions(const Region& a, const gfx::Rect& b) {
   Region result = a;
   result.Subtract(b);
   return result;
@@ -112,7 +112,7 @@ inline Region IntersectRegions(const Region& a, const Region& b) {
   return result;
 }
 
-inline Region IntersectRegions(const Region& a, gfx::Rect b) {
+inline Region IntersectRegions(const Region& a, const gfx::Rect& b) {
   Region result = a;
   result.Intersect(b);
   return result;
@@ -124,7 +124,7 @@ inline Region UnionRegions(const Region& a, const Region& b) {
   return result;
 }
 
-inline Region UnionRegions(const Region& a, gfx::Rect b) {
+inline Region UnionRegions(const Region& a, const gfx::Rect& b) {
   Region result = a;
   result.Union(b);
   return result;