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 b90d28d19ad4d1424dc7b388372223df367ca5b7..3373d4b356167981ff24c3ae3eea2b9951c86ec7 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"
@@ -225,11 +227,11 @@ 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) {
@@ -260,7 +262,7 @@ 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;
+  base::SmallMap<base::hash_map<TileMapKey, gfx::Rect>, 16> remove_tiles;
   gfx::Rect expanded_live_tiles_rect =
       tiling_data_.ExpandRectIgnoringBordersToTileBounds(live_tiles_rect_);
   for (Region::Iterator iter(layer_invalidation); iter.has_rect();
@@ -284,15 +286,20 @@ 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());
-      }
+      // This also adds the TileMapKey to the map.
+      remove_tiles[iter.index()].Union(content_rect);
     }
   }
 
-  for (const auto& key : new_tile_keys)
-    CreateTile(key.first, key.second);
+  for (const auto& pair : remove_tiles) {
+    const TileMapKey& key = pair.first;
+    const gfx::Rect& invalid_content_rect = pair.second;
+    Tile::Id old_id(0);
+    if (RemoveTileAt(key.first, key.second, &old_id) && recreate_tiles) {
+      if (Tile* tile = CreateTile(key.first, key.second))
+        tile->SetInvalidated(invalid_content_rect, old_id);
+    }
+  }
 }
 
 bool PictureLayerTiling::ShouldCreateTileAt(int i, int j) const {
@@ -490,10 +497,12 @@ 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) {

[vmpstr, 2015/05/15 20:54:21]

FWIW, now that you've changed Tile::id() to be > 0, this function can just
return Tile::Id with 0 indicating "no tile was erased" (unless the id
overflows). 

   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;
 }
@@ -650,7 +659,7 @@ 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.