Add a Physical Web data source

ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm

Index: ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm
diff --git a/ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm b/ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm
new file mode 100644
index 0000000000000000000000000000000000000000..44a746ad0554ad58cc40b062a101c7b36917a443
--- /dev/null
+++ b/ios/chrome/common/physical_web/ios_chrome_physical_web_data_source.mm
@@ -0,0 +1,45 @@
+// 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)];
+  [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) {
+    metadata.reset(new base::ListValue());
+  }
+  return metadata;
+}
+
+bool IOSChromePhysicalWebDataSource::HasUnresolvedDiscoveries() {
+  return [scanner_ unresolvedBeaconsCount] > 0;
+}
+
+IOSChromePhysicalWebDataSource::IOSChromePhysicalWebDataSource() {}
+
+IOSChromePhysicalWebDataSource::~IOSChromePhysicalWebDataSource() {
+  StopDiscovery();
+}