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

cc/tiles/picture_layer_tiling_set.h

Index: cc/tiles/picture_layer_tiling_set.h
diff --git a/cc/tiles/picture_layer_tiling_set.h b/cc/tiles/picture_layer_tiling_set.h
index dfa059265228416d67c1920dc6c4b98d346cfe97..9fcb1b7c5ab1ba477b3c4beb7f5d219ebf7012e0 100644
--- a/cc/tiles/picture_layer_tiling_set.h
+++ b/cc/tiles/picture_layer_tiling_set.h
@@ -44,7 +44,8 @@ class CC_EXPORT PictureLayerTilingSet {
       PictureLayerTilingClient* client,
       int tiling_interest_area_padding,
       float skewport_target_time_in_seconds,
-      int skewport_extrapolation_limit_in_screen_pixels);
+      int skewport_extrapolation_limit_in_screen_pixels,
+      float max_preraster_distance);
 
   ~PictureLayerTilingSet();
 
@@ -206,7 +207,8 @@ class CC_EXPORT PictureLayerTilingSet {
       PictureLayerTilingClient* client,
       int tiling_interest_area_padding,
       float skewport_target_time_in_seconds,
-      int skewport_extrapolation_limit_in_screen_pixels);
+      int skewport_extrapolation_limit_in_screen_pixels,
+      float max_preraster_distance);
 
   void CopyTilingsAndPropertiesFromPendingTwin(
       const PictureLayerTilingSet* pending_twin_set,
@@ -235,6 +237,7 @@ class CC_EXPORT PictureLayerTilingSet {
   const int skewport_extrapolation_limit_in_screen_pixels_;
   WhichTree tree_;
   PictureLayerTilingClient* client_;
+  const float max_preraster_distance_;
   // State saved for computing velocities based on finite differences.
   // .front() of the list refers to the most recent FrameVisibleRect.
   std::list<FrameVisibleRect> visible_rect_history_;