Record the initial state of the Physical Web at startup

ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm

Index: ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm
diff --git a/ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm b/ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm
index 80c074479920ed699f1e66ac5d5ba901b6548518..5293afe62e727f45cba70570e8b796f508f23254 100644
--- a/ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm
+++ b/ios/chrome/browser/physical_web/ios_chrome_physical_web_data_source.mm
@@ -6,9 +6,15 @@
 
 #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();