cc: Change preraster/predecode split to be half of max skewport extent.

cc/tiles/picture_layer_tiling.h

Index: cc/tiles/picture_layer_tiling.h
diff --git a/cc/tiles/picture_layer_tiling.h b/cc/tiles/picture_layer_tiling.h
index fcd06ace8cd20025ba207cfd4e22593ac392a40c..354719f28d676c1bc7441bc07de0c73f21e1b240 100644
--- a/cc/tiles/picture_layer_tiling.h
+++ b/cc/tiles/picture_layer_tiling.h
@@ -83,7 +83,9 @@ class CC_EXPORT PictureLayerTiling {
   PictureLayerTiling(WhichTree tree,
                      float contents_scale,
                      scoped_refptr<RasterSource> raster_source,
-                     PictureLayerTilingClient* client);
+                     PictureLayerTilingClient* client,
+                     float min_preraster_distance,
+                     float max_preraster_distance);
   ~PictureLayerTiling();
 
   PictureLayerTilingClient* client() const { return client_; }
@@ -324,6 +326,8 @@ class CC_EXPORT PictureLayerTiling {
   PictureLayerTilingClient* const client_;
   const WhichTree tree_;
   scoped_refptr<RasterSource> raster_source_;
+  const float min_preraster_distance_;
+  const float max_preraster_distance_;
   TileResolution resolution_;
   bool may_contain_low_resolution_tiles_;
 
@@ -342,6 +346,7 @@ class CC_EXPORT PictureLayerTiling {
   // Other properties used for tile iteration and prioritization.
   float current_content_to_screen_scale_;
   Occlusion current_occlusion_in_layer_space_;
+  float max_skewport_extent_in_screen_space_;
 
   bool has_visible_rect_tiles_;
   bool has_skewport_rect_tiles_;