Record the initial state of the Physical Web at startup

ios/chrome/browser/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/browser/physical_web/ios_chrome_physical_web_data_source.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/values.h"
+#import "ios/chrome/browser/physical_web/physical_web_initial_state_recorder.h"
 #import "ios/chrome/common/physical_web/physical_web_scanner.h"
 
-IOSChromePhysicalWebDataSource::IOSChromePhysicalWebDataSource() {}
+IOSChromePhysicalWebDataSource::IOSChromePhysicalWebDataSource(
+    PrefService* pref_service) {
+  initialStateRecorder_.reset([[PhysicalWebInitialStateRecorder alloc]
+      initWithPrefService:pref_service]);
+  [initialStateRecorder_ collectAndRecordState];

[rohitrao (ping after 24h), 2016/12/12 12:54:17]

Keeping this object alive forever probably isn't terrible, especially if we can
destroy the CBCentralManager when we're done with it.

Another option would be to add a PhysicalWebInitialStateRecorderDelegate method
that's called when the recording is done, which would allow the owner to destroy
the recorder.  The savings might not be worth the overhead.

[mattreynolds, 2016/12/12 21:48:46]

I modified PWISR to destroy the CBCentralManager after we get the bluetooth
state callback.

I think it's not worth the overhead to destroy the recorder.

+}
 
 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.
@@ skipping 19 matching lines @@
 std::unique_ptr<base::ListValue> IOSChromePhysicalWebDataSource::GetMetadata() {
   if (!scanner_) {
     return base::MakeUnique<base::ListValue>();
   }
   return [scanner_ metadata];
 }
 
 bool IOSChromePhysicalWebDataSource::HasUnresolvedDiscoveries() {
   return [scanner_ unresolvedBeaconsCount] > 0;
 }