Add a Physical Web data source

ios/chrome/common/physical_web/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source_set("physical_web") {
   sources = [
+    "physical_web_data_source_ios.h",
+    "physical_web_data_source_ios.mm",
     "physical_web_device.h",
     "physical_web_device.mm",
     "physical_web_request.h",
     "physical_web_request.mm",
     "physical_web_scanner.h",
     "physical_web_scanner.mm",
     "physical_web_types.h",
     "physical_web_types.mm",
   ]
 
   deps = [
     "//base",
+    "//components/physical_web_data_source",
     "//components/version_info",
     "//device/bluetooth/uribeacon",
     "//google_apis",
     "//ios/web:user_agent",
   ]
 
   libs = [
     "CoreBluetooth.framework",
     "Foundation.framework",
   ]
 }