Revert of cc: Remove tile sharing from tilings.

cc/resources/tile.cc

Index: cc/resources/tile.cc
diff --git a/cc/resources/tile.cc b/cc/resources/tile.cc
index 7467d9330ab217627ac9e973af3ea1087809a8e8..45b4a30816e1958d2065eaffaa4e306d4a75486a 100644
--- a/cc/resources/tile.cc
+++ b/cc/resources/tile.cc
@@ -32,11 +32,14 @@
       flags_(flags),
       tiling_i_index_(-1),
       tiling_j_index_(-1),
+      is_shared_(false),
       required_for_activation_(false),
       required_for_draw_(false),
       id_(s_next_id_++),
       scheduled_priority_(0) {
   set_raster_source(raster_source);
+  for (int i = 0; i <= LAST_TREE; i++)
+    is_occluded_[i] = false;
 }
 
 Tile::~Tile() {
@@ -59,11 +62,11 @@
   // TODO(vmpstr): Remove active and pending priority once tracing is using
   // combined priority or at least can support both.
   res->BeginDictionary("active_priority");
-  priority_.AsValueInto(res);
+  priority_[ACTIVE_TREE].AsValueInto(res);
   res->EndDictionary();
 
   res->BeginDictionary("pending_priority");
-  priority_.AsValueInto(res);
+  priority_[PENDING_TREE].AsValueInto(res);
   res->EndDictionary();
 
   res->BeginDictionary("combined_priority");
@@ -76,7 +79,8 @@
 
   res->SetBoolean("has_resource", HasResource());
   res->SetBoolean("is_using_gpu_memory", HasResource() || HasRasterTask());
-  res->SetString("resolution", TileResolutionToString(priority_.resolution));
+  res->SetString("resolution",
+                 TileResolutionToString(combined_priority().resolution));
 
   res->SetInteger("scheduled_priority", scheduled_priority_);