Reland of: cc: Add occlusion checker as a fixed view of occlusion tracker.

cc/resources/picture_layer_tiling.cc

Index: cc/resources/picture_layer_tiling.cc
diff --git a/cc/resources/picture_layer_tiling.cc b/cc/resources/picture_layer_tiling.cc
index 0d50658061e0ed0e3b015e4d54980d9b9b38fc49..0229879da606154bf09e76d505383be0bb7c2178 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -15,7 +15,6 @@
 #include "cc/base/math_util.h"
 #include "cc/resources/tile.h"
 #include "cc/resources/tile_priority.h"
-#include "cc/trees/occlusion_tracker.h"
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/safe_integer_conversions.h"
@@ -540,9 +539,7 @@ void PictureLayerTiling::UpdateTilePriorities(
     const gfx::Rect& visible_layer_rect,
     float ideal_contents_scale,
     double current_frame_time_in_seconds,
-    const OcclusionTracker<LayerImpl>* occlusion_tracker,
-    const LayerImpl* render_target,
-    const gfx::Transform& draw_transform) {
+    const Occlusion& occlusion_in_layer_space) {
   if (!NeedsUpdateForFrameAtTime(current_frame_time_in_seconds)) {
     // This should never be zero for the purposes of has_ever_been_updated().
     DCHECK_NE(current_frame_time_in_seconds, 0.0);
@@ -605,16 +602,10 @@ void PictureLayerTiling::UpdateTilePriorities(
     tile->SetPriority(tree, now_priority);
 
     // Set whether tile is occluded or not.
-    bool is_occluded = false;
-    if (occlusion_tracker) {
-      gfx::Rect tile_query_rect = ScaleToEnclosingRect(
-          IntersectRects(tile->content_rect(), visible_rect_in_content_space),
-          1.0f / contents_scale_);
-      // TODO(vmpstr): Remove render_target and draw_transform from the
-      // parameters so they can be hidden from the tiling.
-      is_occluded = occlusion_tracker->Occluded(
-          render_target, tile_query_rect, draw_transform);
-    }
+    gfx::Rect tile_query_rect = ScaleToEnclosingRect(
+        IntersectRects(tile->content_rect(), visible_rect_in_content_space),
+        1.0f / contents_scale_);
+    bool is_occluded = occlusion_in_layer_space.IsOccluded(tile_query_rect);
     tile->set_is_occluded(tree, is_occluded);
   }