cc: Don't swap PictureLayerTilingSet on activate.

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 e9e3b86180a0dba8a297dc77235f6f84224fe191..8eb95d80f91021603960cadd613e4b336e37fe43 100644
--- a/cc/resources/picture_layer_tiling.cc
+++ b/cc/resources/picture_layer_tiling.cc
@@ -105,10 +105,6 @@ PictureLayerTiling::~PictureLayerTiling() {
     it->second->set_shared(false);
 }
 
-void PictureLayerTiling::SetClient(PictureLayerTilingClient* client) {
-  client_ = client;
-}
-
 Tile* PictureLayerTiling::CreateTile(int i,
                                      int j,
                                      const PictureLayerTiling* twin_tiling) {
@@ -167,6 +163,13 @@ void PictureLayerTiling::CreateMissingTilesInLiveTilesRect() {
   VerifyLiveTilesRect();
 }
 
+void PictureLayerTiling::CreateSharedTilesFromPending(
+    const PictureLayerTiling& other) {
+  DCHECK_EQ(&other, client_->GetPendingOrActiveTwinTiling(this));
+  SetLiveTilesRect(other.live_tiles_rect());
+  DCHECK_EQ(other.tiles_.size(), tiles_.size());
+}
+
 void PictureLayerTiling::UpdateTilesToCurrentRasterSource(
     RasterSource* raster_source,
     const Region& layer_invalidation,
@@ -210,10 +213,10 @@ void PictureLayerTiling::UpdateTilesToCurrentRasterSource(
           tiling_data_.TileYIndexFromSrcCoord(live_tiles_rect_.bottom() - 1);
     }
 
-    // There is no recycled twin since this is run on the pending tiling.
+    // There is no recycled twin since this is run on the pending tiling
+    // during commit, and on the active tree during activate.
     PictureLayerTiling* recycled_twin = NULL;
     DCHECK_EQ(recycled_twin, client_->GetRecycledTwinTiling(this));
-    DCHECK_EQ(PENDING_TREE, client_->GetTree());
 
     // Drop tiles outside the new layer bounds if the layer shrank.
     for (int i = after_right + 1; i <= before_right; ++i) {
@@ -250,23 +253,22 @@ void PictureLayerTiling::UpdateTilesToCurrentRasterSource(
     Invalidate(layer_invalidation);
   }
 
-  for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
-    it->second->set_raster_source(raster_source);
+  // 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.
+  // TODO(danakj): Clean this up, pass it in or make it a separate function call
+  // or something.
+  // TODO(danakj): This breaks if we commit to active tree! We really need to do
+  // this for the sync tree.
+  bool set_tiles_to_raster_source = client_->GetTree() == PENDING_TREE;
+  if (set_tiles_to_raster_source) {
+    for (TileMap::const_iterator it = tiles_.begin(); it != tiles_.end(); ++it)
+      it->second->set_raster_source(raster_source);
+  }
   VerifyLiveTilesRect();
 }
 
-void PictureLayerTiling::RemoveTilesInRegion(const Region& layer_region) {
-  bool recreate_invalidated_tiles = false;
-  DoInvalidate(layer_region, recreate_invalidated_tiles);
-}
-
 void PictureLayerTiling::Invalidate(const Region& layer_region) {
-  bool recreate_invalidated_tiles = true;
-  DoInvalidate(layer_region, recreate_invalidated_tiles);
-}
-
-void PictureLayerTiling::DoInvalidate(const Region& layer_region,
-                                      bool recreate_invalidated_tiles) {
   std::vector<TileMapKey> new_tile_keys;
   gfx::Rect expanded_live_tiles_rect =
       tiling_data_.ExpandRectIgnoringBordersToTileBounds(live_tiles_rect_);
@@ -291,20 +293,24 @@ void PictureLayerTiling::DoInvalidate(const Region& layer_region,
              &tiling_data_, content_rect, include_borders);
          iter;
          ++iter) {
-      // There is no recycled twin since this is run on the pending tiling.
+      // There is no recycled twin for the peding tree during commit, or for the
+      // active tree during activation.
       PictureLayerTiling* recycled_twin = NULL;
       DCHECK_EQ(recycled_twin, client_->GetRecycledTwinTiling(this));
-      DCHECK_EQ(PENDING_TREE, client_->GetTree());
       if (RemoveTileAt(iter.index_x(), iter.index_y(), recycled_twin))
         new_tile_keys.push_back(iter.index());
     }
   }
 
-  if (recreate_invalidated_tiles && !new_tile_keys.empty()) {
+  if (!new_tile_keys.empty()) {
+    // During commit to the pending tree, invalidations can never be shared with
+    // the active tree since the active tree has different content there.
+    // However, during activation, invalidations on the active tree can be
+    // shared with the pending tree always.
+    const PictureLayerTiling* twin_tiling = nullptr;
+    if (client_->GetTree() == ACTIVE_TREE)
+      twin_tiling = client_->GetPendingOrActiveTwinTiling(this);
     for (size_t i = 0; i < new_tile_keys.size(); ++i) {
-      // Don't try to share a tile with the twin layer, it's been invalidated so
-      // we have to make our own tile here.
-      const PictureLayerTiling* twin_tiling = NULL;
       CreateTile(new_tile_keys[i].first, new_tile_keys[i].second, twin_tiling);
     }
   }