[#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..2cf2f560807eb3fe1a4f03770f2f6ccb2a6af26d 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);
@@ -36,10 +36,10 @@ 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);