cc: Make tiling interest rect calc based on viewport.

cc/resources/picture_layer_tiling.h

Index: cc/resources/picture_layer_tiling.h
diff --git a/cc/resources/picture_layer_tiling.h b/cc/resources/picture_layer_tiling.h
index edd139997ab9f377e54d758e2c8e95d7dfa1ee72..05f2d3f4cf2b58b0e9d68e5accf04189dea2809d 100644
--- a/cc/resources/picture_layer_tiling.h
+++ b/cc/resources/picture_layer_tiling.h
@@ -68,7 +68,7 @@ class CC_EXPORT PictureLayerTiling {
       float contents_scale,
       scoped_refptr<RasterSource> raster_source,
       PictureLayerTilingClient* client,
-      size_t max_tiles_for_interest_area,
+      float tiling_interest_area_viewport_multiplier,
       float skewport_target_time_in_seconds,
       int skewport_extrapolation_limit_in_content_pixels);
 
@@ -227,7 +227,7 @@ class CC_EXPORT PictureLayerTiling {
                      float contents_scale,
                      scoped_refptr<RasterSource> raster_source,
                      PictureLayerTilingClient* client,
-                     size_t max_tiles_for_interest_area,
+                     float tiling_interest_area_viewport_multiplier,
                      float skewport_target_time_in_seconds,
                      int skewport_extrapolation_limit_in_content_pixels);
   void SetLiveTilesRect(const gfx::Rect& live_tiles_rect);
@@ -308,7 +308,7 @@ class CC_EXPORT PictureLayerTiling {
   }
   void RemoveTilesInRegion(const Region& layer_region, bool recreate_tiles);
 
-  const size_t max_tiles_for_interest_area_;
+  const float tiling_interest_area_viewport_multiplier_;
   const float skewport_target_time_in_seconds_;
   const int skewport_extrapolation_limit_in_content_pixels_;