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

cc/resources/picture_layer_tiling.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/picture_layer_tiling.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
 
 #include "base/debug/trace_event.h"
 #include "base/debug/trace_event_argument.h"
 #include "base/logging.h"
 #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"
 #include "ui/gfx/size_conversions.h"
 
 namespace cc {
 namespace {
 
 const float kSoonBorderDistanceInScreenPixels = 312.f;
 
@@ skipping 504 matching lines @@
   // Finally, ensure that visible rect is contained in the skewport.
   skewport.Union(visible_rect_in_content_space);
   return skewport;
 }
 
 void PictureLayerTiling::UpdateTilePriorities(
     WhichTree tree,
     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);
     return;
   }
 
   gfx::Rect visible_rect_in_content_space =
       gfx::ScaleToEnclosingRect(visible_layer_rect, contents_scale_);
 
   if (tiling_size().IsEmpty()) {
@@ skipping 42 matching lines @@
        ++iter) {
     TileMap::iterator find = tiles_.find(iter.index());
     if (find == tiles_.end())
       continue;
     has_visible_rect_tiles_ = true;
     Tile* tile = find->second.get();
 
     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);
   }
 
   // Assign soon priority to skewport tiles.
   has_skewport_rect_tiles_ = false;
   for (TilingData::DifferenceIterator iter(
            &tiling_data_, skewport, visible_rect_in_content_space);
        iter;
        ++iter) {
     TileMap::iterator find = tiles_.find(iter.index());
@@ skipping 572 matching lines @@
   DCHECK(*this);
   do {
     ++current_eviction_tiles_index_;
   } while (current_eviction_tiles_index_ != eviction_tiles_->size() &&
            !(*eviction_tiles_)[current_eviction_tiles_index_]->HasResources());
 
   return *this;
 }
 
 }  // namespace cc