Add a Physical Web data source

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"
+
+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]);
+  [scanner_
+      setNetworkRequestEnabled:static_cast<BOOL>(network_request_enabled)];

[sdefresne, 2016/08/02 22:23:36]

There is no need to cast a bool to a BOOL. I think passing the value as is
should work. If this is not the case, then I would recommend to use
initialisation syntax instead, so use one of the two following syntaxes:

[scanner_ setNetworkRequestEnabled:network_request_enabled];
[scanner_ setNetworkRequestEnabled:BOOL{network_request_enabled}];

[mattreynolds, 2016/08/04 00:56:12]

Done.

+  [scanner_ start];
+}
+
+void IOSChromePhysicalWebDataSource::StopDiscovery() {
+  [scanner_ stop];
+  scanner_.reset();
+}
+
+std::unique_ptr<base::ListValue> IOSChromePhysicalWebDataSource::GetMetadata() {
+  std::unique_ptr<base::ListValue> metadata = [scanner_ metadata];
+  if (metadata.get() == NULL) {

[sdefresne, 2016/08/02 22:23:36]

if (!metadata)
  metadata = base::MakeUnique<base::ListValue>();

[mattreynolds, 2016/08/04 00:56:12]

Done.

+    metadata.reset(new base::ListValue());
+  }
+  return metadata;
+}
+
+bool IOSChromePhysicalWebDataSource::HasUnresolvedDiscoveries() {
+  return [scanner_ unresolvedBeaconsCount] > 0;
+}
+
+IOSChromePhysicalWebDataSource::IOSChromePhysicalWebDataSource() {}

[sdefresne, 2016/08/02 22:23:36]

Please keep method in the same order as in the header file.

[mattreynolds, 2016/08/04 00:56:12]

Done.

+
+IOSChromePhysicalWebDataSource::~IOSChromePhysicalWebDataSource() {
+  StopDiscovery();
+}