cc: Remove tile sharing from tilings.

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>
@@ skipping 61 matching lines @@
                                             contents_scale)).IsEmpty())
       << "Tiling created with scale too small as contents become empty."
       << " Layer bounds: " << raster_source_->GetSize().ToString()
       << " Contents scale: " << contents_scale;
 
   tiling_data_.SetTilingSize(content_bounds);
   tiling_data_.SetMaxTextureSize(tile_size);
 }
 
 PictureLayerTiling::~PictureLayerTiling() {
-  for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
-    it->second->set_shared(false);
 }
 
 // static
 float PictureLayerTiling::CalculateSoonBorderDistance(
     const gfx::Rect& visible_rect_in_content_space,
     float content_to_screen_scale) {
   float max_dimension = std::max(visible_rect_in_content_space.width(),
                                  visible_rect_in_content_space.height());
   return std::min(
       kMaxSoonBorderDistanceInScreenPixels / content_to_screen_scale,
       max_dimension * kSoonBorderDistanceViewportPercentage);
 }
 
-Tile* PictureLayerTiling::CreateTile(int i,
-                                     int j,
-                                     const PictureLayerTiling* twin_tiling,
-                                     PictureLayerTiling* recycled_twin) {
-  // Can't have both a (pending or active) twin and a recycled twin tiling.
-  DCHECK_IMPLIES(twin_tiling, !recycled_twin);
-  DCHECK_IMPLIES(recycled_twin, !twin_tiling);
+Tile* PictureLayerTiling::CreateTile(int i, int j) {
   TileMapKey key(i, j);
   DCHECK(tiles_.find(key) == tiles_.end());
 
   gfx::Rect paint_rect = tiling_data_.TileBoundsWithBorder(i, j);
   gfx::Rect tile_rect = paint_rect;
   tile_rect.set_size(tiling_data_.max_texture_size());
 
-  // Check our twin for a valid tile.
-  if (twin_tiling &&
-      tiling_data_.max_texture_size() ==
-      twin_tiling->tiling_data_.max_texture_size()) {
-    if (Tile* candidate_tile = twin_tiling->TileAt(i, j)) {
-      gfx::Rect rect =
-          gfx::ScaleToEnclosingRect(paint_rect, 1.0f / contents_scale_);
-      const Region* invalidation = client_->GetPendingInvalidation();
-      if (!invalidation || !invalidation->Intersects(rect)) {
-        DCHECK(!candidate_tile->is_shared());
-        DCHECK_EQ(i, candidate_tile->tiling_i_index());
-        DCHECK_EQ(j, candidate_tile->tiling_j_index());
-        candidate_tile->set_shared(true);
-        tiles_[key] = candidate_tile;
-        return candidate_tile;
-      }
-    }
+  if (!raster_source_->CoversRect(tile_rect, contents_scale_)) {
+    failed_tile_indices_.push_back(key);

[enne (OOO), 2015/04/20 22:36:28]

failed could be a better word.  What about remove_on_activation_indices?

It's a little out of the way to record tiles inside of CreateTile, as it depends
on calling code to call CreateTile for every tile that could exist on the active
tree, so that it'll get removed later.  It seems like it'd be better for calling
code to do this?  Although, maybe that's a double covers check unless you just
assume that CreateTile will always succeed.

Also, I think this could be smarter, as the recording rect doesn't have holes in
it anymore (although I guess we do hold onto uninvalidated recording grid cells
forever outside of it, but that shouldn't be applicable here).  It seems like we
could just find the rects that are no longer covered and drop tiles that
intersect them.

[vmpstr, 2015/04/22 18:38:57]

Done.
I'm not sure what you're proposing here. CreateTile is protected, so the caller
is only this class and friends (and tests, I guess). Or are you proposing
changing the raster source interface to expose the region/rect it has recorded?

+    return nullptr;
   }
 
-  if (!raster_source_->CoversRect(tile_rect, contents_scale_))
-    return nullptr;
-
-  // Create a new tile because our twin didn't have a valid one.
-  scoped_refptr<Tile> tile = client_->CreateTile(contents_scale_, tile_rect);
-  DCHECK(!tile->is_shared());
+  scoped_refptr<Tile> tile =
+      client_->CreateTile(contents_scale_, tile_rect, &raster_source_);
   tile->set_tiling_index(i, j);
   tiles_[key] = tile;
-
-  if (recycled_twin) {
-    DCHECK(recycled_twin->tiles_.find(key) == recycled_twin->tiles_.end());
-    // Do what recycled_twin->CreateTile() would do.
-    tile->set_shared(true);
-    recycled_twin->tiles_[key] = tile;
-  }
   return tile.get();
 }
 
 void PictureLayerTiling::CreateMissingTilesInLiveTilesRect() {
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
-  // There is no recycled twin during commit from the main thread which is when
-  // this occurs.
-  PictureLayerTiling* null_recycled_twin = nullptr;
-  DCHECK_EQ(null_recycled_twin, client_->GetRecycledTwinTiling(this));
   bool include_borders = false;
-  for (TilingData::Iterator iter(
-           &tiling_data_, live_tiles_rect_, include_borders);
-       iter;
-       ++iter) {
+  for (TilingData::Iterator iter(&tiling_data_, live_tiles_rect_,
+                                 include_borders);
+       iter; ++iter) {
     TileMapKey key = iter.index();
     TileMap::iterator find = tiles_.find(key);
     if (find != tiles_.end())
       continue;
-    CreateTile(key.first, key.second, twin_tiling, null_recycled_twin);
+
+    if (ShouldCreateTileAt(key.first, key.second))
+      CreateTile(key.first, key.second);
   }
-
   VerifyLiveTilesRect(false);
 }
 
-void PictureLayerTiling::CloneTilesAndPropertiesFrom(
-    const PictureLayerTiling& twin_tiling) {
-  DCHECK_EQ(&twin_tiling, client_->GetPendingOrActiveTwinTiling(this));
+void PictureLayerTiling::TakeTilesAndPropertiesFrom(
+    PictureLayerTiling* pending_twin) {
+  TRACE_EVENT0("cc", "TakeTilesAndPropertiesFrom");
+  SetRasterSourceAndResize(pending_twin->raster_source_);
 
-  SetRasterSourceAndResize(twin_tiling.raster_source_);
-  DCHECK_EQ(twin_tiling.contents_scale_, contents_scale_);
-  DCHECK_EQ(twin_tiling.raster_source_, raster_source_);
-  DCHECK_EQ(twin_tiling.tile_size().ToString(), tile_size().ToString());
+  for (const auto& key : pending_twin->failed_tile_indices_)
+    RemoveTileAt(key.first, key.second);
 
-  resolution_ = twin_tiling.resolution_;
+  pending_twin->failed_tile_indices_.clear();
+  failed_tile_indices_.clear();
 
-  SetLiveTilesRect(twin_tiling.live_tiles_rect());
+  resolution_ = pending_twin->resolution_;
+  if (live_tiles_rect_.IsEmpty())
+    live_tiles_rect_ = pending_twin->live_tiles_rect();
+  else
+    SetLiveTilesRect(pending_twin->live_tiles_rect());
 
-  // Recreate unshared tiles.
-  std::vector<TileMapKey> to_remove;
-  for (const auto& tile_map_pair : tiles_) {
-    TileMapKey key = tile_map_pair.first;
-    Tile* tile = tile_map_pair.second.get();
-    if (!tile->is_shared())
-      to_remove.push_back(key);
+  for (auto& tile_pair : pending_twin->tiles_) {
+    Tile* tile = tile_pair.second.get();
+    tile->set_raster_source(&raster_source_);
+    tiles_[tile_pair.first] = tile_pair.second;
   }
-  // The recycled twin does not exist since there is a pending twin (which is
-  // |twin_tiling|).
-  PictureLayerTiling* null_recycled_twin = nullptr;
-  DCHECK_EQ(null_recycled_twin, client_->GetRecycledTwinTiling(this));
-  for (const auto& key : to_remove) {
-    RemoveTileAt(key.first, key.second, null_recycled_twin);
-    CreateTile(key.first, key.second, &twin_tiling, null_recycled_twin);
-  }
+  pending_twin->tiles_.clear();
 
-  // Create any missing tiles from the |twin_tiling|.
-  for (const auto& tile_map_pair : twin_tiling.tiles_) {
-    TileMapKey key = tile_map_pair.first;
-    Tile* tile = tile_map_pair.second.get();
-    if (!tile->is_shared())
-      CreateTile(key.first, key.second, &twin_tiling, null_recycled_twin);
-  }
+  VerifyLiveTilesRect(false);
 
-  DCHECK_EQ(twin_tiling.tiles_.size(), tiles_.size());
-#if DCHECK_IS_ON()
-  for (const auto& tile_map_pair : tiles_)
-    DCHECK(tile_map_pair.second->is_shared());
-  VerifyLiveTilesRect(false);
-#endif
-
-  UpdateTilePriorityRects(twin_tiling.current_content_to_screen_scale_,
-                          twin_tiling.current_visible_rect_,
-                          twin_tiling.current_skewport_rect_,
-                          twin_tiling.current_soon_border_rect_,
-                          twin_tiling.current_eventually_rect_,
-                          twin_tiling.current_occlusion_in_layer_space_);
+  SetTilePriorityRects(pending_twin->current_content_to_screen_scale_,
+                       pending_twin->current_visible_rect_,
+                       pending_twin->current_skewport_rect_,
+                       pending_twin->current_soon_border_rect_,
+                       pending_twin->current_eventually_rect_,
+                       pending_twin->current_occlusion_in_layer_space_);
 }
 
 void PictureLayerTiling::SetRasterSourceAndResize(
     scoped_refptr<RasterSource> raster_source) {
   DCHECK(!raster_source->IsSolidColor());
   gfx::Size old_layer_bounds = raster_source_->GetSize();
   raster_source_.swap(raster_source);
   gfx::Size new_layer_bounds = raster_source_->GetSize();
   gfx::Size content_bounds =
       gfx::ToCeiledSize(gfx::ScaleSize(new_layer_bounds, contents_scale_));
@@ skipping 32 matching lines @@
   int after_bottom = -1;
   if (!live_tiles_rect_.IsEmpty()) {
     after_right =
         tiling_data_.TileXIndexFromSrcCoord(live_tiles_rect_.right() - 1);
     after_bottom =
         tiling_data_.TileYIndexFromSrcCoord(live_tiles_rect_.bottom() - 1);
   }
 
   // There is no recycled twin since this is run on the pending tiling
   // during commit, and on the active tree during activate.
-  PictureLayerTiling* null_recycled_twin = nullptr;
-  DCHECK_EQ(null_recycled_twin, client_->GetRecycledTwinTiling(this));
-
   // Drop tiles outside the new layer bounds if the layer shrank.
   for (int i = after_right + 1; i <= before_right; ++i) {
     for (int j = before_top; j <= before_bottom; ++j)
-      RemoveTileAt(i, j, null_recycled_twin);
+      RemoveTileAt(i, j);
   }
   for (int i = before_left; i <= after_right; ++i) {
     for (int j = after_bottom + 1; j <= before_bottom; ++j)
-      RemoveTileAt(i, j, null_recycled_twin);
+      RemoveTileAt(i, j);
   }
 
-  // If the layer grew, the live_tiles_rect_ is not changed, but a new row
-  // and/or column of tiles may now exist inside the same live_tiles_rect_.
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
   if (after_right > before_right) {
     DCHECK_EQ(after_right, before_right + 1);
-    for (int j = before_top; j <= after_bottom; ++j)
-      CreateTile(after_right, j, twin_tiling, null_recycled_twin);
+    for (int j = before_top; j <= after_bottom; ++j) {
+      if (ShouldCreateTileAt(after_right, j))
+        CreateTile(after_right, j);
+    }
   }
   if (after_bottom > before_bottom) {
     DCHECK_EQ(after_bottom, before_bottom + 1);
-    for (int i = before_left; i <= before_right; ++i)
-      CreateTile(i, after_bottom, twin_tiling, null_recycled_twin);
+    for (int i = before_left; i <= before_right; ++i) {
+      if (ShouldCreateTileAt(i, after_bottom))
+        CreateTile(i, after_bottom);
+    }
   }
 }
 
 void PictureLayerTiling::Invalidate(const Region& layer_invalidation) {
+  // We don't need to invalidate the pending tiling, since
+  // CreateMissingTilesInLiveTilesRect will populate all the tiles that we need.
+  if (client_->GetTree() == PENDING_TREE)
+    return;
+
+  // We only invalidate the active tiling when it's orphaned: it has no pending
+  // twin, so it's slated for removal in the future.
+  DCHECK(!client_->GetPendingOrActiveTwinTiling(this));
   if (live_tiles_rect_.IsEmpty())
     return;
   std::vector<TileMapKey> new_tile_keys;
   gfx::Rect expanded_live_tiles_rect =
       tiling_data_.ExpandRectIgnoringBordersToTileBounds(live_tiles_rect_);
   for (Region::Iterator iter(layer_invalidation); iter.has_rect();
        iter.next()) {
     gfx::Rect layer_rect = iter.rect();
     gfx::Rect content_rect =
         gfx::ScaleToEnclosingRect(layer_rect, contents_scale_);
     // Consider tiles inside the live tiles rect even if only their border
     // pixels intersect the invalidation. But don't consider tiles outside
     // the live tiles rect with the same conditions, as they won't exist.
     int border_pixels = tiling_data_.border_texels();
     content_rect.Inset(-border_pixels, -border_pixels);
     // Avoid needless work by not bothering to invalidate where there aren't
     // tiles.
     content_rect.Intersect(expanded_live_tiles_rect);
     if (content_rect.IsEmpty())
       continue;
     // Since the content_rect includes border pixels already, don't include
     // borders when iterating to avoid double counting them.
     bool include_borders = false;
-    for (TilingData::Iterator iter(
-             &tiling_data_, content_rect, include_borders);
-         iter;
-         ++iter) {
-      // There is no recycled twin for the pending tree during commit, or for
-      // the active tree during activation.
-      PictureLayerTiling* null_recycled_twin = nullptr;
-      DCHECK_EQ(null_recycled_twin, client_->GetRecycledTwinTiling(this));
-      if (RemoveTileAt(iter.index_x(), iter.index_y(), null_recycled_twin))
+    for (
+        TilingData::Iterator iter(&tiling_data_, content_rect, include_borders);
+        iter; ++iter) {
+      if (RemoveTileAt(iter.index_x(), iter.index_y()))
         new_tile_keys.push_back(iter.index());
     }
   }
 
-  if (!new_tile_keys.empty()) {
-    // During commit from the main thread, invalidations can never be shared
-    // with the active tree since the active tree has different content there.
-    // And when invalidating an active-tree tiling, it means there was no
-    // pending tiling to clone from.
-    const PictureLayerTiling* null_twin_tiling = nullptr;
-    PictureLayerTiling* null_recycled_twin = nullptr;
-    DCHECK_EQ(null_recycled_twin, client_->GetRecycledTwinTiling(this));
-    for (size_t i = 0; i < new_tile_keys.size(); ++i) {
-      CreateTile(new_tile_keys[i].first, new_tile_keys[i].second,
-                 null_twin_tiling, null_recycled_twin);
-    }
-  }
+  for (const auto& key : new_tile_keys)
+    CreateTile(key.first, key.second);
 }
 
-void PictureLayerTiling::SetRasterSourceOnTiles() {
-  // Shared (ie. non-invalidated) tiles on the pending tree are updated to use
-  // the new raster source. When this raster source is activated, the raster
-  // source will remain valid for shared tiles in the active tree.
-  for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
-    it->second->set_raster_source(raster_source_);
-  VerifyLiveTilesRect(false);
+bool PictureLayerTiling::ShouldCreateTileAt(int i, int j) const {
+  // Active tree should always create a tile. The reason for this is that active
+  // tree represents content that we draw on screen, which means that whenever
+  // we check whether a tile should exist somewhere, the answer is yes. This
+  // doesn't mean it will actually be created (if raster source doesn't cover
+  // the tile for instance). Pending tree, on the other hand, should only be
+  // creating tiles that are different from the current active tree, which is
+  // represented by the logic in the rest of the function.
+  if (client_->GetTree() == ACTIVE_TREE)
+    return true;
+
+  // If the pending tree has no active twin, then it needs to create all tiles.
+  const PictureLayerTiling* active_twin =
+      client_->GetPendingOrActiveTwinTiling(this);
+  if (!active_twin)
+    return true;
+
+  // Pending tree will override the entire active tree if indices don't match.
+  if (!TilingMatchesTileIndices(active_twin))
+    return true;
+
+  gfx::Rect paint_rect = tiling_data_.TileBoundsWithBorder(i, j);
+  gfx::Rect tile_rect = paint_rect;
+  tile_rect.set_size(tiling_data_.max_texture_size());
+
+  // If the active tree can't create a tile, because of its raster source, then
+  // the pending tree should create one.
+  if (!active_twin->raster_source()->CoversRect(tile_rect, contents_scale()))
+    return true;
+
+  const Region* layer_invalidation = client_->GetPendingInvalidation();
+  gfx::Rect layer_rect =
+      gfx::ScaleToEnclosingRect(tile_rect, 1.f / contents_scale());
+
+  // If this tile is invalidated, then the pending tree should create one.
+  if (layer_invalidation && layer_invalidation->Intersects(layer_rect))
+    return true;
+
+  // If the active tree doesn't have a tile here, but it's in the pending tree's
+  // visible rect, then the pending tree should create a tile. This can happen
+  // if the pending visible rect is outside of the active tree's live tiles
+  // rect. In those situations, we need to block activation until we're ready to
+  // display content, which will have to come from the pending tree.
+  if (!active_twin->TileAt(i, j) && current_visible_rect_.Intersects(tile_rect))
+    return true;
+
+  // In all other cases, the pending tree doesn't need to create a tile.
+  return false;
+}
+
+bool PictureLayerTiling::TilingMatchesTileIndices(
+    const PictureLayerTiling* twin) const {
+  return tiling_data_.max_texture_size() ==
+         twin->tiling_data_.max_texture_size();
 }
 
 PictureLayerTiling::CoverageIterator::CoverageIterator()
     : tiling_(NULL),
       current_tile_(NULL),
       tile_i_(0),
       tile_j_(0),
       left_(0),
       top_(0),
       right_(-1),
@@ skipping 121 matching lines @@
   texture_rect.Scale(dest_to_content_scale_,
                      dest_to_content_scale_);
   texture_rect.Intersect(gfx::Rect(tiling_->tiling_size()));
   if (texture_rect.IsEmpty())
     return texture_rect;
   texture_rect.Offset(-tex_origin.OffsetFromOrigin());
 
   return texture_rect;
 }
 
-bool PictureLayerTiling::RemoveTileAt(int i,
-                                      int j,
-                                      PictureLayerTiling* recycled_twin) {
+bool PictureLayerTiling::RemoveTileAt(int i, int j) {
   TileMap::iterator found = tiles_.find(TileMapKey(i, j));
   if (found == tiles_.end())
     return false;
-  found->second->set_shared(false);
   tiles_.erase(found);
-  if (recycled_twin) {
-    // Recycled twin does not also have a recycled twin, so pass null.
-    recycled_twin->RemoveTileAt(i, j, nullptr);
-  }
   return true;
 }
 
 void PictureLayerTiling::Reset() {
   live_tiles_rect_ = gfx::Rect();
-  PictureLayerTiling* recycled_twin = client_->GetRecycledTwinTiling(this);
-  for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it) {
-    it->second->set_shared(false);
-    if (recycled_twin)
-      recycled_twin->RemoveTileAt(it->first.first, it->first.second, nullptr);
-  }
   tiles_.clear();
 }
 
 gfx::Rect PictureLayerTiling::ComputeSkewport(
     double current_frame_time_in_seconds,
     const gfx::Rect& visible_rect_in_content_space) const {
   gfx::Rect skewport = visible_rect_in_content_space;
   if (skewport.IsEmpty())
     return skewport;
 
@@ skipping 89 matching lines @@
   float content_to_screen_scale = ideal_contents_scale / contents_scale_;
   gfx::Rect soon_border_rect = visible_rect_in_content_space;
   float border = CalculateSoonBorderDistance(visible_rect_in_content_space,
                                              content_to_screen_scale);
   soon_border_rect.Inset(-border, -border, -border, -border);
 
   UpdateVisibleRectHistory(current_frame_time_in_seconds,
                            visible_rect_in_content_space);
   last_viewport_in_layer_space_ = viewport_in_layer_space;
 
+  SetTilePriorityRects(content_to_screen_scale, visible_rect_in_content_space,
+                       skewport, soon_border_rect, eventually_rect,
+                       occlusion_in_layer_space);
   SetLiveTilesRect(eventually_rect);
-  UpdateTilePriorityRects(
-      content_to_screen_scale, visible_rect_in_content_space, skewport,
-      soon_border_rect, eventually_rect, occlusion_in_layer_space);
   return true;
 }
 
-void PictureLayerTiling::UpdateTilePriorityRects(
+void PictureLayerTiling::SetTilePriorityRects(
     float content_to_screen_scale,
     const gfx::Rect& visible_rect_in_content_space,
     const gfx::Rect& skewport,
     const gfx::Rect& soon_border_rect,
     const gfx::Rect& eventually_rect,
     const Occlusion& occlusion_in_layer_space) {
   current_visible_rect_ = visible_rect_in_content_space;
   current_skewport_rect_ = skewport;
   current_soon_border_rect_ = soon_border_rect;
   current_eventually_rect_ = eventually_rect;
@@ skipping 10 matching lines @@
 
 void PictureLayerTiling::SetLiveTilesRect(
     const gfx::Rect& new_live_tiles_rect) {
   DCHECK(new_live_tiles_rect.IsEmpty() ||
          gfx::Rect(tiling_size()).Contains(new_live_tiles_rect))
       << "tiling_size: " << tiling_size().ToString()
       << " new_live_tiles_rect: " << new_live_tiles_rect.ToString();
   if (live_tiles_rect_ == new_live_tiles_rect)
     return;
 
-  PictureLayerTiling* recycled_twin = client_->GetRecycledTwinTiling(this);
-
   // Iterate to delete all tiles outside of our new live_tiles rect.
-  for (TilingData::DifferenceIterator iter(&tiling_data_,
-                                           live_tiles_rect_,
+  for (TilingData::DifferenceIterator iter(&tiling_data_, live_tiles_rect_,
                                            new_live_tiles_rect);
-       iter;
-       ++iter) {
-    RemoveTileAt(iter.index_x(), iter.index_y(), recycled_twin);
+       iter; ++iter) {
+    RemoveTileAt(iter.index_x(), iter.index_y());
   }
 
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
-
   // Iterate to allocate new tiles for all regions with newly exposed area.
-  for (TilingData::DifferenceIterator iter(&tiling_data_,
-                                           new_live_tiles_rect,
+  for (TilingData::DifferenceIterator iter(&tiling_data_, new_live_tiles_rect,
                                            live_tiles_rect_);
-       iter;
-       ++iter) {
+       iter; ++iter) {
     TileMapKey key(iter.index());
-    CreateTile(key.first, key.second, twin_tiling, recycled_twin);
+    if (ShouldCreateTileAt(key.first, key.second))
+      CreateTile(key.first, key.second);
   }
 
   live_tiles_rect_ = new_live_tiles_rect;
   VerifyLiveTilesRect(false);
-  if (recycled_twin) {
-    recycled_twin->live_tiles_rect_ = live_tiles_rect_;
-    recycled_twin->VerifyLiveTilesRect(true);
-  }
 }
 
 void PictureLayerTiling::VerifyLiveTilesRect(bool is_on_recycle_tree) const {
 #if DCHECK_IS_ON()
   for (auto it = tiles_.begin(); it != tiles_.end(); ++it) {
     if (!it->second.get())
       continue;
     DCHECK(it->first.first < tiling_data_.num_tiles_x())
         << this << " " << it->first.first << "," << it->first.second
         << " num_tiles_x " << tiling_data_.num_tiles_x() << " live_tiles_rect "
         << live_tiles_rect_.ToString();
     DCHECK(it->first.second < tiling_data_.num_tiles_y())
         << this << " " << it->first.first << "," << it->first.second
         << " num_tiles_y " << tiling_data_.num_tiles_y() << " live_tiles_rect "
         << live_tiles_rect_.ToString();
     DCHECK(tiling_data_.TileBounds(it->first.first, it->first.second)
                .Intersects(live_tiles_rect_))
         << this << " " << it->first.first << "," << it->first.second
         << " tile bounds "
         << tiling_data_.TileBounds(it->first.first, it->first.second).ToString()
         << " live_tiles_rect " << live_tiles_rect_.ToString();
-    DCHECK_IMPLIES(is_on_recycle_tree, it->second->is_shared());
   }
 #endif
 }
 
 bool PictureLayerTiling::IsTileOccluded(const Tile* tile) const {
-  DCHECK(tile);
+  // If this tile is not occluded on this tree, then it is not occluded.
+  if (!IsTileOccludedOnCurrentTree(tile))
+    return false;
 
+  // Otherwise, if this is the pending tree, we're done and the tile is
+  // occluded.
+  if (client_->GetTree() == PENDING_TREE)
+    return true;
+
+  // On the active tree however, we need to check if this tile will be
+  // unoccluded upon activation, in which case it has to be considered
+  // unoccluded.
+  const PictureLayerTiling* pending_twin =
+      client_->GetPendingOrActiveTwinTiling(this);
+  if (pending_twin) {
+    // If there's a pending tile in the same position. Or if the pending twin
+    // would have to be creating all tiles, then we don't need to worry about
+    // occlusion on the twin.
+    if (!TilingMatchesTileIndices(pending_twin) ||
+        pending_twin->TileAt(tile->tiling_i_index(), tile->tiling_j_index())) {
+      return true;
+    }
+    return pending_twin->IsTileOccludedOnCurrentTree(tile);
+  }
+  return true;
+}
+
+bool PictureLayerTiling::IsTileOccludedOnCurrentTree(const Tile* tile) const {
   if (!current_occlusion_in_layer_space_.HasOcclusion())
     return false;
-
   gfx::Rect tile_query_rect =
       gfx::IntersectRects(tile->content_rect(), current_visible_rect_);
-
   // Explicitly check if the tile is outside the viewport. If so, we need to
   // return false, since occlusion for this tile is unknown.
-  // TODO(vmpstr): Since the current visible rect is really a viewport in
-  // layer space, we should probably clip tile query rect to tiling bounds
-  // or live tiles rect.
   if (tile_query_rect.IsEmpty())
     return false;
 
   if (contents_scale_ != 1.f) {
     tile_query_rect =
-        gfx::ScaleToEnclosingRect(tile_query_rect, 1.0f / contents_scale_);
+        gfx::ScaleToEnclosingRect(tile_query_rect, 1.f / contents_scale_);
   }
-
   return current_occlusion_in_layer_space_.IsOccluded(tile_query_rect);
 }
 
-bool PictureLayerTiling::IsTileRequiredForActivationIfVisible(
-    const Tile* tile) const {
-  DCHECK_EQ(PENDING_TREE, client_->GetTree());
+bool PictureLayerTiling::IsTileRequiredForActivation(const Tile* tile) const {
+  if (client_->GetTree() == PENDING_TREE) {
+    if (!can_require_tiles_for_activation_)
+      return false;
 
-  // This function assumes that the tile is visible (i.e. in the viewport).  The
-  // caller needs to make sure that this condition is met to ensure we don't
-  // block activation on tiles outside of the viewport.
+    if (resolution_ != HIGH_RESOLUTION)
+      return false;
 
-  // If we are not allowed to mark tiles as required for activation, then don't
-  // do it.
-  if (!can_require_tiles_for_activation_)
+    if (IsTileOccluded(tile))
+      return false;
+
+    bool tile_is_visible =
+        tile->content_rect().Intersects(current_visible_rect_);
+    if (!tile_is_visible)
+      return false;
+
+    if (client_->RequiresHighResToDraw())
+      return true;
+
+    const PictureLayerTiling* active_twin =
+        client_->GetPendingOrActiveTwinTiling(this);
+    if (!active_twin || !TilingMatchesTileIndices(active_twin))
+      return true;
+
+    if (active_twin->raster_source()->GetSize() != raster_source()->GetSize())
+      return true;
+
+    if (active_twin->current_visible_rect_ != current_visible_rect_)
+      return true;
+
+    Tile* twin_tile =
+        active_twin->TileAt(tile->tiling_i_index(), tile->tiling_j_index());
+    if (!twin_tile)
+      return false;
+    return true;
+  }
+
+  DCHECK(client_->GetTree() == ACTIVE_TREE);
+  const PictureLayerTiling* pending_twin =
+      client_->GetPendingOrActiveTwinTiling(this);
+  // If we don't have a pending tree, or the pending tree will overwrite the
+  // given tile, then it is not required for activation.
+  if (!pending_twin || !TilingMatchesTileIndices(pending_twin) ||
+      pending_twin->TileAt(tile->tiling_i_index(), tile->tiling_j_index())) {
+    return false;
+  }
+  // Otherwise, ask the pending twin if this tile is required for activation.
+  return pending_twin->IsTileRequiredForActivation(tile);
+}
+
+bool PictureLayerTiling::IsTileRequiredForDraw(const Tile* tile) const {
+  if (client_->GetTree() == PENDING_TREE)
     return false;
 
   if (resolution_ != HIGH_RESOLUTION)
     return false;
 
-  if (IsTileOccluded(tile))
+  bool tile_is_visible = current_visible_rect_.Intersects(tile->content_rect());
+  if (!tile_is_visible)
     return false;
 
-  if (client_->RequiresHighResToDraw())
-    return true;
-
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
-  if (!twin_tiling)
-    return true;
-
-  if (twin_tiling->raster_source()->GetSize() != raster_source()->GetSize())
-    return true;
-
-  if (twin_tiling->current_visible_rect_ != current_visible_rect_)
-    return true;
-
-  Tile* twin_tile =
-      twin_tiling->TileAt(tile->tiling_i_index(), tile->tiling_j_index());
-  // If twin tile is missing, it might not have a recording, so we don't need
-  // this tile to be required for activation.
-  if (!twin_tile)
+  if (IsTileOccludedOnCurrentTree(tile))
     return false;
-
-  return true;
-}
-
-bool PictureLayerTiling::IsTileRequiredForDrawIfVisible(
-    const Tile* tile) const {
-  DCHECK_EQ(ACTIVE_TREE, client_->GetTree());
-
-  // This function assumes that the tile is visible (i.e. in the viewport).
-
-  if (resolution_ != HIGH_RESOLUTION)
-    return false;
-
-  if (IsTileOccluded(tile))
-    return false;
-
   return true;
 }
 
 void PictureLayerTiling::UpdateTileAndTwinPriority(Tile* tile) const {
-  WhichTree tree = client_->GetTree();
-  WhichTree twin_tree = tree == ACTIVE_TREE ? PENDING_TREE : ACTIVE_TREE;
-
-  tile->SetPriority(tree, ComputePriorityForTile(tile));
-  UpdateRequiredStateForTile(tile, tree);
-
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
-  if (!tile->is_shared() || !twin_tiling) {
-    tile->SetPriority(twin_tree, TilePriority());
-    tile->set_is_occluded(twin_tree, false);
-    if (twin_tree == PENDING_TREE)
-      tile->set_required_for_activation(false);
-    else
-      tile->set_required_for_draw(false);
-    return;
-  }
-
-  tile->SetPriority(twin_tree, twin_tiling->ComputePriorityForTile(tile));
-  twin_tiling->UpdateRequiredStateForTile(tile, twin_tree);
-}
-
-void PictureLayerTiling::UpdateRequiredStateForTile(Tile* tile,
-                                                    WhichTree tree) const {
-  if (tile->priority(tree).priority_bin == TilePriority::NOW) {
-    if (tree == PENDING_TREE) {
-      tile->set_required_for_activation(
-          IsTileRequiredForActivationIfVisible(tile));
-    } else {
-      tile->set_required_for_draw(IsTileRequiredForDrawIfVisible(tile));
-    }
-    tile->set_is_occluded(tree, IsTileOccluded(tile));
-    return;
-  }
-
-  // Non-NOW bin tiles are not required or occluded.
-  if (tree == PENDING_TREE)
-    tile->set_required_for_activation(false);
-  else
-    tile->set_required_for_draw(false);
-  tile->set_is_occluded(tree, false);
+  tile->set_priority(ComputePriorityForTile(tile));
+  tile->set_is_occluded(IsTileOccluded(tile));
+  tile->set_required_for_activation(IsTileRequiredForActivation(tile));
+  tile->set_required_for_draw(IsTileRequiredForDraw(tile));
 }
 
 void PictureLayerTiling::VerifyAllTilesHaveCurrentRasterSource() const {
 #if DCHECK_IS_ON()
   for (const auto& tile_pair : tiles_)
     DCHECK_EQ(raster_source_.get(), tile_pair.second->raster_source());
 #endif
 }
 
 TilePriority PictureLayerTiling::ComputePriorityForTile(
     const Tile* tile) const {
   // TODO(vmpstr): See if this can be moved to iterators.
   TilePriority::PriorityBin max_tile_priority_bin =
       client_->GetMaxTilePriorityBin();
 
   DCHECK_EQ(TileAt(tile->tiling_i_index(), tile->tiling_j_index()), tile);
   gfx::Rect tile_bounds =
       tiling_data_.TileBounds(tile->tiling_i_index(), tile->tiling_j_index());
 
   if (max_tile_priority_bin <= TilePriority::NOW &&
       current_visible_rect_.Intersects(tile_bounds)) {
     return TilePriority(resolution_, TilePriority::NOW, 0);
   }
 
+  if (max_tile_priority_bin <= TilePriority::SOON &&
+      pending_visible_rect().Intersects(tile_bounds)) {
+    return TilePriority(resolution_, TilePriority::SOON, 0);
+  }
+
   DCHECK_GT(current_content_to_screen_scale_, 0.f);
   float distance_to_visible =
       current_visible_rect_.ManhattanInternalDistance(tile_bounds) *
       current_content_to_screen_scale_;
 
   if (max_tile_priority_bin <= TilePriority::SOON &&
       (current_soon_border_rect_.Intersects(tile_bounds) ||
        current_skewport_rect_.Intersects(tile_bounds))) {
     return TilePriority(resolution_, TilePriority::SOON, distance_to_visible);
   }
 
   return TilePriority(resolution_, TilePriority::EVENTUALLY,
                       distance_to_visible);
 }
 
 void PictureLayerTiling::GetAllTilesAndPrioritiesForTracing(
     std::map<const Tile*, TilePriority>* tile_map) const {
-  const PictureLayerTiling* twin_tiling =
-      client_->GetPendingOrActiveTwinTiling(this);
   for (const auto& tile_pair : tiles_) {
     const Tile* tile = tile_pair.second.get();
     const TilePriority& priority = ComputePriorityForTile(tile);
-    // If the tile is shared, it means the twin also has the same tile.
-    // Otherwise, use the default priority.
-    const TilePriority& twin_priority =
-        (twin_tiling && tile->is_shared())
-            ? twin_tiling->ComputePriorityForTile(tile)
-            : TilePriority();
-
     // Store combined priority.
-    (*tile_map)[tile] = TilePriority(priority, twin_priority);
+    (*tile_map)[tile] = priority;
   }
 }
 
 void PictureLayerTiling::AsValueInto(
     base::trace_event::TracedValue* state) const {
   state->SetInteger("num_tiles", tiles_.size());
   state->SetDouble("content_scale", contents_scale_);
   MathUtil::AddToTracedValue("visible_rect", current_visible_rect_, state);
   MathUtil::AddToTracedValue("skewport_rect", current_skewport_rect_, state);
   MathUtil::AddToTracedValue("soon_rect", current_soon_border_rect_, state);
@@ skipping 156 matching lines @@
       break;
   }
 
   gfx::Rect result(origin_x, origin_y, width, height);
   if (cache)
     cache->previous_result = result;
   return result;
 }
 
 }  // namespace cc