Record the initial state of the Physical Web at startup

ios/chrome/browser/application_context_impl.cc

 // Copyright 2014 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.
 
 #include "ios/chrome/browser/application_context_impl.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "base/command_line.h"
@@ skipping 268 matching lines @@
 
 CRLSetFetcher* ApplicationContextImpl::GetCRLSetFetcher() {
   DCHECK(thread_checker_.CalledOnValidThread());
   if (!crl_set_fetcher_) {
     crl_set_fetcher_ = new CRLSetFetcher;
   }
   return crl_set_fetcher_.get();
 }
 
 physical_web::PhysicalWebDataSource*
 ApplicationContextImpl::GetPhysicalWebDataSource() {

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

When is this method called for the first time?  Creating the data source
automatically starts the metrics collection, and the bluetooth callback is
scheduled on the main thread.  Is this something that we could delay for N
seconds after startup, so we're not running non-essential code in the critical
path of startup?

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

It's first called during [MainController startUpBrowserForegroundInitialization]
when the browser view is switched.

I added a 10 second delay so we won't record the state until after
initialization is complete. The delay could affect the recorded state (eg, user
could grant the Location app permission before the delay expires) but it's
unlikely to be significant.

The preference state likely WILL change during the delay period since we have
logic to auto-enable the pref when certain conditions are met. We intentionally
capture the pref state before the delay to avoid grabbing it after the
auto-enable logic has executed.

   DCHECK(thread_checker_.CalledOnValidThread());
   if (!physical_web_data_source_) {
-    physical_web_data_source_ = CreateIOSChromePhysicalWebDataSource();
+    physical_web_data_source_ =
+        CreateIOSChromePhysicalWebDataSource(GetLocalState());
     DCHECK(physical_web_data_source_);
   }
   return physical_web_data_source_.get();
 }
 
 void ApplicationContextImpl::SetApplicationLocale(const std::string& locale) {
   DCHECK(thread_checker_.CalledOnValidThread());
   application_locale_ = locale;
   translate::TranslateDownloadManager::GetInstance()->set_application_locale(
       application_locale_);
@@ skipping 41 matching lines @@
           base::SequencedWorkerPool::SKIP_ON_SHUTDOWN));
 
   gcm_driver_ = gcm::CreateGCMDriverDesktop(
       base::WrapUnique(new gcm::GCMClientFactory), GetLocalState(), store_path,
       GetSystemURLRequestContext(), ::GetChannel(),
       IOSChromeGCMProfileServiceFactory::GetProductCategoryForSubtypes(),
       web::WebThread::GetTaskRunnerForThread(web::WebThread::UI),
       web::WebThread::GetTaskRunnerForThread(web::WebThread::IO),
       blocking_task_runner);
 }