A host of micro-optimizations and a refactor of TimeForBoundsToIntersect

cc/picture_layer_tiling.cc

Index: cc/picture_layer_tiling.cc
diff --git a/cc/picture_layer_tiling.cc b/cc/picture_layer_tiling.cc
index ad460f1c3114cfb6bd70821465f372e369b8a5fc..7b1fb6381eb16b41b4adc66e81c0e3b5fcf1918f 100644
--- a/cc/picture_layer_tiling.cc
+++ b/cc/picture_layer_tiling.cc
@@ -4,6 +4,7 @@
 
 #include "cc/picture_layer_tiling.h"
 
+#include "base/debug/trace_event.h"
 #include "cc/math_util.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
@@ -297,6 +298,7 @@ void PictureLayerTiling::UpdateTilePriorities(
     const gfx::Transform& last_screen_transform,
     const gfx::Transform& current_screen_transform,
     double time_delta) {
+  TRACE_EVENT0("cc", "PictureLayerTiling::UpdateTilePriorities");
   gfx::Rect content_rect = ContentRect();
   if (content_rect.IsEmpty())
     return;
@@ -331,12 +333,13 @@ void PictureLayerTiling::UpdateTilePriorities(
           last_scale,
           last_scale) + last_offset;
 
+      priority.distance_to_visible_in_pixels =

[enne (OOO), 2013/01/30 06:53:56]

Please don't create unnecessary diff churn by moving things around.

[whunt, 2013/01/30 21:07:33]

This is a performance optimization.

[enne (OOO), 2013/01/30 21:50:12]

Could you explain?

+          TilePriority::manhattanDistance(current_screen_rect, view_rect);
+
       priority.time_to_visible_in_seconds =
           TilePriority::TimeForBoundsToIntersect(
               last_screen_rect, current_screen_rect, time_delta, view_rect);
 
-      priority.distance_to_visible_in_pixels =
-          TilePriority::manhattanDistance(current_screen_rect, view_rect);
       it->second->set_priority(tree, priority);
     }
   }
@@ -362,12 +365,13 @@ void PictureLayerTiling::UpdateTilePriorities(
       gfx::RectF last_screen_rect  = MathUtil::mapClippedRect(
           last_screen_transform, last_layer_content_rect);
 
+      priority.distance_to_visible_in_pixels =
+          TilePriority::manhattanDistance(current_screen_rect, view_rect);
+
       priority.time_to_visible_in_seconds =
           TilePriority::TimeForBoundsToIntersect(
               last_screen_rect, current_screen_rect, time_delta, view_rect);
 
-      priority.distance_to_visible_in_pixels =
-          TilePriority::manhattanDistance(current_screen_rect, view_rect);
       it->second->set_priority(tree, priority);
     }
   }