cc: Rename PictureLayerTiling(Set) Iterator to CoverageIterator

cc/resources/picture_layer_tiling_set.h

Index: cc/resources/picture_layer_tiling_set.h
diff --git a/cc/resources/picture_layer_tiling_set.h b/cc/resources/picture_layer_tiling_set.h
index 901bb9b95c236d681eb22b24390d9c4c4e39bd04..ee28b387f0546dd3a00b11df32a92494ac75e1c6 100644
--- a/cc/resources/picture_layer_tiling_set.h
+++ b/cc/resources/picture_layer_tiling_set.h
@@ -71,13 +71,13 @@ class CC_EXPORT PictureLayerTilingSet {
   // through null tiles with valid geometry_rect() until the rect is full.
   // If all tiles have resources, the union of all geometry_rects will
   // exactly fill rect with no overlap.
-  class CC_EXPORT Iterator {
+  class CC_EXPORT CoverageIterator {
    public:
-    Iterator(const PictureLayerTilingSet* set,
+    CoverageIterator(const PictureLayerTilingSet* set,
       float contents_scale,
       gfx::Rect content_rect,
       float ideal_contents_scale);
-    ~Iterator();
+    ~CoverageIterator();
 
     // Visible rect (no borders), always in the space of rect,
     // regardless of the relative contents scale of the tiling.
@@ -90,7 +90,7 @@ class CC_EXPORT PictureLayerTilingSet {
     Tile* operator->() const;
     Tile* operator*() const;
 
-    Iterator& operator++();
+    CoverageIterator& operator++();
     operator bool() const;
 
     PictureLayerTiling* CurrentTiling();
@@ -101,7 +101,7 @@ class CC_EXPORT PictureLayerTilingSet {
     const PictureLayerTilingSet* set_;
     float contents_scale_;
     float ideal_contents_scale_;
-    PictureLayerTiling::Iterator tiling_iter_;
+    PictureLayerTiling::CoverageIterator tiling_iter_;
     int current_tiling_;
     int ideal_tiling_;