Record the initial state of the Physical Web at startup

ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm

-// 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.
-
-#import "ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.h"
-
-#include "base/memory/ptr_util.h"
-#include "base/values.h"
-#import "ios/chrome/common/physical_web/physical_web_scanner.h"
-
-IOSChromePhysicalWebDataSource::IOSChromePhysicalWebDataSource() {}
-
-IOSChromePhysicalWebDataSource::~IOSChromePhysicalWebDataSource() {
-  StopDiscovery();
-}
-
-void IOSChromePhysicalWebDataSource::StartDiscovery(
-    bool network_request_enabled) {
-  // If there are unresolved beacons it means the scanner is started but does
-  // not have network requests enabled. In this case we should avoid recreating
-  // the scanner as it would clear the cache of nearby beacons.
-  if (network_request_enabled && HasUnresolvedDiscoveries()) {
-    [scanner_ setNetworkRequestEnabled:YES];
-    return;
-  }
-
-  [scanner_ stop];
-  scanner_.reset([[PhysicalWebScanner alloc] initWithDelegate:nil]);
-
-  // Configure the scanner to notify us when a URL is no longer nearby.
-  [scanner_ setOnLostDetectionEnabled:YES];
-  [scanner_ setNetworkRequestEnabled:network_request_enabled];
-  [scanner_ start];
-}
-
-void IOSChromePhysicalWebDataSource::StopDiscovery() {
-  [scanner_ stop];
-  scanner_.reset();
-}
-
-std::unique_ptr<base::ListValue> IOSChromePhysicalWebDataSource::GetMetadata() {
-  if (!scanner_) {
-    return base::MakeUnique<base::ListValue>();
-  }
-  return [scanner_ metadata];
-}
-
-bool IOSChromePhysicalWebDataSource::HasUnresolvedDiscoveries() {
-  return [scanner_ unresolvedBeaconsCount] > 0;
-}