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 d90eb42782f82c117f3c7898a6374c655f8c5aab..cfa9b6099fdf78f2a854e9fc881c506e68a677c0 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/point_conversions.h"
 #include "ui/gfx/rect_conversions.h"
@@ -335,6 +336,7 @@ void PictureLayerTiling::UpdateTilePriorities(
     const gfx::Transform& current_screen_transform,
     int current_source_frame_number,
     double current_frame_time) {
+  TRACE_EVENT0("cc", "PictureLayerTiling::UpdateTilePriorities");
   gfx::Rect content_rect = ContentRect();
   if (content_rect.IsEmpty())
     return;
@@ -425,12 +427,12 @@ void PictureLayerTiling::UpdateTilePriorities(
           last_scale,
           last_scale) + last_offset;
 
-      float time_to_visible_in_seconds =
-          TilePriority::TimeForBoundsToIntersect(
-              last_screen_rect, current_screen_rect, time_delta, view_rect);
       float distance_to_visible_in_pixels =
           TilePriority::manhattanDistance(current_screen_rect, view_rect);
 
+      float time_to_visible_in_seconds =
+          TilePriority::TimeForBoundsToIntersect(
+              last_screen_rect, current_screen_rect, time_delta, view_rect);
       TilePriority priority(
           resolution_,
           time_to_visible_in_seconds,
@@ -462,11 +464,12 @@ void PictureLayerTiling::UpdateTilePriorities(
       gfx::RectF last_screen_rect  = MathUtil::mapClippedRect(
           last_screen_transform, last_layer_content_rect);
 
+      float distance_to_visible_in_pixels =
+          TilePriority::manhattanDistance(current_screen_rect, view_rect);
+
       float time_to_visible_in_seconds =
           TilePriority::TimeForBoundsToIntersect(
               last_screen_rect, current_screen_rect, time_delta, view_rect);
-      float distance_to_visible_in_pixels =
-          TilePriority::manhattanDistance(current_screen_rect, view_rect);
 
       TilePriority priority(
           resolution_,