cc: Partial tile update for one-copy raster.

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 de2cb4a19f1cca0e9587f3943e83c2d837072fe7..17a6c1f133207383100cb329762c31e97e352fc6 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -9,6 +9,8 @@
 #include <limits>
 #include <set>
 
+#include "base/containers/hash_tables.h"
+#include "base/containers/small_map.h"
 #include "base/logging.h"
 #include "base/trace_event/trace_event.h"
 #include "base/trace_event/trace_event_argument.h"
@@ -227,11 +229,11 @@ void PictureLayerTiling::SetRasterSourceAndResize(
   // 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);
+      RemoveTileAt(i, j, nullptr);
   }
   for (int i = before_left; i <= after_right; ++i) {
     for (int j = after_bottom + 1; j <= before_bottom; ++j)
-      RemoveTileAt(i, j);
+      RemoveTileAt(i, j, nullptr);
   }
 
   if (after_right > before_right) {
@@ -262,7 +264,11 @@ void PictureLayerTiling::RemoveTilesInRegion(const Region& layer_invalidation,
   // twin, so it's slated for removal in the future.
   if (live_tiles_rect_.IsEmpty())
     return;
-  std::vector<TileMapKey> new_tile_keys;
+  struct RemoveTileData {
+    gfx::Rect invalid_content_rect;
+    Tile::Id invalid_id;
+  };
+  base::SmallMap<base::hash_map<TileMapKey, RemoveTileData>, 16> remove_tiles;
   gfx::Rect expanded_live_tiles_rect =
       tiling_data_.ExpandRectIgnoringBordersToTileBounds(live_tiles_rect_);
   for (Region::Iterator iter(layer_invalidation); iter.has_rect();
@@ -286,15 +292,21 @@ void PictureLayerTiling::RemoveTilesInRegion(const Region& layer_invalidation,
     for (
         TilingData::Iterator iter(&tiling_data_, content_rect, include_borders);
         iter; ++iter) {
-      if (RemoveTileAt(iter.index_x(), iter.index_y())) {
-        if (recreate_tiles)
-          new_tile_keys.push_back(iter.index());
-      }
+      RemoveTileData& remove_tile_data = remove_tiles[iter.index()];

[vmpstr, 2015/05/14 22:28:27]

At a first glance, this seems to be changing behaviour:

- We should only be recreating tiles if recreate_tiles is true.
- We should only be creating tiles in regions where we removed tiles.

^ those two are no longer true. 

I'd prefer to keep old behaviour. I think you had a right thing before where you
moved RemoveTileAt to be in the second loop. The first loop just need to
accumulate rects (so the small map can be Key -> Rect, I think). The second loop
would do something like

if (RemoveTile(...) && recreate_tile) {
  CreateTile(...);
  tile->set_stuff(...);
}

[danakj, 2015/05/14 22:35:00]

Ya you're very right and your suggestion is spot on. Fixed this.

+      remove_tile_data.invalid_content_rect.Union(content_rect);
+      Tile::Id old_id;
+      if (RemoveTileAt(iter.index_x(), iter.index_y(), &old_id))
+        remove_tile_data.invalid_id = old_id;
     }
   }
 
-  for (const auto& key : new_tile_keys)
-    CreateTile(key.first, key.second);
+  for (const auto& pair : remove_tiles) {
+    const TileMapKey& key = pair.first;
+    const RemoveTileData& remove_tile_data = pair.second;
+    Tile* tile = CreateTile(key.first, key.second);
+    tile->SetInvalidatedRect(remove_tile_data.invalid_content_rect);
+    tile->SetInvalidatedId(remove_tile_data.invalid_id);
+  }
 }
 
 void PictureLayerTiling::SetRasterSourceOnTiles() {
@@ -500,10 +512,12 @@ gfx::RectF PictureLayerTiling::CoverageIterator::texture_rect() const {
   return texture_rect;
 }
 
-bool PictureLayerTiling::RemoveTileAt(int i, int j) {
+bool PictureLayerTiling::RemoveTileAt(int i, int j, Tile::Id* id) {
   TileMap::iterator found = tiles_.find(TileMapKey(i, j));
   if (found == tiles_.end())
     return false;
+  if (id)
+    *id = found->second->id();
   tiles_.erase(found);
   return true;
 }
@@ -661,7 +675,7 @@ void PictureLayerTiling::SetLiveTilesRect(
   for (TilingData::DifferenceIterator iter(&tiling_data_, live_tiles_rect_,
                                            new_live_tiles_rect);
        iter; ++iter) {
-    RemoveTileAt(iter.index_x(), iter.index_y());
+    RemoveTileAt(iter.index_x(), iter.index_y(), nullptr);
   }
 
   // Iterate to allocate new tiles for all regions with newly exposed area.