Query tiles: Fix a crash due to sub-tile not found in response.

- If in the server side, the translation is not ready, even if the
top-level tile has a sub-level tile id, but the sub-level tile could be
not existing in the response.

- Remove the DCHECK, we just ignore this sub-tile in client side.

Change-Id: Ie1f8fab56dc100abc66ff13d55a197fe7704caf4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2202127Reviewed-by: David Trainor <dtrainor@chromium.org>
Commit-Queue: Hesen Zhang <hesen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#768873}

components/query_tiles/internal/proto_conversion.cc

@@ -40,12 +40,13 @@ void ResponseToTile(
   }
 
   for (const auto& id : response.sub_tile_ids()) {
-    DCHECK(sub_tiles_from_response.count(id));
-    auto sub_tile_from_response = sub_tiles_from_response.at(id);
-    auto new_sub_tile = std::make_unique<Tile>();
-    ResponseToTile(sub_tile_from_response, new_sub_tile.get(),
-                   sub_tiles_from_response);
-    tile->sub_tiles.emplace_back(std::move(new_sub_tile));
+    if (sub_tiles_from_response.count(id)) {
+      auto sub_tile_from_response = sub_tiles_from_response.at(id);
+      auto new_sub_tile = std::make_unique<Tile>();
+      ResponseToTile(sub_tile_from_response, new_sub_tile.get(),
+                     sub_tiles_from_response);
+      tile->sub_tiles.emplace_back(std::move(new_sub_tile));
+    }
   }
 }