cc: Stop passing the occlusion explicitly to UpdateTiles.

cc/layers/picture_layer_impl.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/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <set>
@@ skipping 390 matching lines @@
                          on_demand_missing_tile_count);
   }
 
   // Aggressively remove any tilings that are not seen to save memory. Note
   // that this is at the expense of doing cause more frequent re-painting. A
   // better scheme would be to maintain a tighter visible_content_rect for the
   // finer tilings.
   CleanUpTilingsOnActiveLayer(last_append_quads_tilings_);
 }
 
-bool PictureLayerImpl::UpdateTiles(const Occlusion& occlusion_in_content_space,
-                                   bool resourceless_software_draw) {
+bool PictureLayerImpl::UpdateTiles(bool resourceless_software_draw) {
   DCHECK_EQ(1.f, contents_scale_x());
   DCHECK_EQ(1.f, contents_scale_y());
 
   if (!resourceless_software_draw) {
     visible_rect_for_tile_priority_ = visible_content_rect();
   }
 
   if (!CanHaveTilings()) {
     ideal_page_scale_ = 0.f;
     ideal_device_scale_ = 0.f;
@@ skipping 22 matching lines @@
   DCHECK(raster_device_scale_);
   DCHECK(raster_source_scale_);
   DCHECK(raster_contents_scale_);
   DCHECK(low_res_raster_contents_scale_);
 
   was_screen_space_transform_animating_ =
       draw_properties().screen_space_transform_is_animating;
 
   if (draw_transform_is_animating())
     raster_source_->SetShouldAttemptToUseDistanceFieldText();
-  return UpdateTilePriorities(occlusion_in_content_space);
-}
-
-bool PictureLayerImpl::UpdateTilePriorities(
-    const Occlusion& occlusion_in_content_space) {
-  DCHECK_IMPLIES(raster_source_->IsSolidColor(), tilings_->num_tilings() == 0);
 
   double current_frame_time_in_seconds =
       (layer_tree_impl()->CurrentBeginFrameArgs().frame_time -
        base::TimeTicks()).InSecondsF();
   UpdateViewportRectForTilePriorityInContentSpace();
 
   // The tiling set can require tiles for activation any of the following
   // conditions are true:
   // - This layer produced a high-res or non-ideal-res tile last frame.
   // - We're in requires high res to draw mode.
   // - We're not in smoothness takes priority mode.
   // To put different, the tiling set can't require tiles for activation if
   // we're in smoothness mode and only used low-res or checkerboard to draw last
   // frame and we don't need high res to draw.
   //
   // The reason for this is that we should be able to activate sooner and get a
   // more up to date recording, so we don't run out of recording on the active
   // tree.
   bool can_require_tiles_for_activation =
       !only_used_low_res_last_append_quads_ || RequiresHighResToDraw() ||
       !layer_tree_impl()->SmoothnessTakesPriority();
 
+  static const Occlusion kEmptyOcclusion;
+  const Occlusion& occlusion_in_content_space =
+      layer_tree_impl()->settings().use_occlusion_for_tile_prioritization
+          ? draw_properties().occlusion_in_content_space
+          : kEmptyOcclusion;
+
   // Pass |occlusion_in_content_space| for |occlusion_in_layer_space| since
   // they are the same space in picture layer, as contents scale is always 1.
   bool updated = tilings_->UpdateTilePriorities(
       viewport_rect_for_tile_priority_in_content_space_, ideal_contents_scale_,
       current_frame_time_in_seconds, occlusion_in_content_space,
       can_require_tiles_for_activation);
   return updated;
 }
 
 void PictureLayerImpl::UpdateViewportRectForTilePriorityInContentSpace() {
@@ skipping 719 matching lines @@
 
 bool PictureLayerImpl::IsOnActiveOrPendingTree() const {
   return !layer_tree_impl()->IsRecycleTree();
 }
 
 bool PictureLayerImpl::HasValidTilePriorities() const {
   return IsOnActiveOrPendingTree() && IsDrawnRenderSurfaceLayerListMember();
 }
 
 }  // namespace cc