NQE: Notify observer as soon as it is added

chrome/browser/net/nqe/ui_network_quality_estimator_service.cc

 // 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.
 
 #include "chrome/browser/net/nqe/ui_network_quality_estimator_service.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
@@ skipping 108 matching lines @@
 
   void InitializeOnIOThread(IOThread* io_thread) {
     DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
     if (!io_thread->globals()->network_quality_estimator)
       return;
     network_quality_estimator_ =
         io_thread->globals()->network_quality_estimator.get();
     if (!network_quality_estimator_)
       return;
     network_quality_estimator_->AddEffectiveConnectionTypeObserver(this);
-    content::BrowserThread::PostTask(
-        content::BrowserThread::UI, FROM_HERE,
-        base::Bind(
-            &UINetworkQualityEstimatorService::EffectiveConnectionTypeChanged,
-            service_,
-            network_quality_estimator_->GetEffectiveConnectionType()));
   }
 
   // net::NetworkQualityEstimator::EffectiveConnectionTypeObserver
   // implementation:
   void OnEffectiveConnectionTypeChanged(
       net::EffectiveConnectionType type) override {
     DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
     content::BrowserThread::PostTask(
         content::BrowserThread::UI, FROM_HERE,
         base::Bind(
@@ skipping 63 matching lines @@
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   type_ = type;
   for (auto& observer : effective_connection_type_observer_list_)
     observer.OnEffectiveConnectionTypeChanged(type);
 }
 
 void UINetworkQualityEstimatorService::AddEffectiveConnectionTypeObserver(
     net::NetworkQualityEstimator::EffectiveConnectionTypeObserver* observer) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   effective_connection_type_observer_list_.AddObserver(observer);
+
+  // Notify the |observer| on the next message pump since |observer| may not
+  // be completely set up for receiving the callbacks.
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI, FROM_HERE,
+      base::Bind(&UINetworkQualityEstimatorService::
+                     NotifyEffectiveConnectionTypeObserverIfPresent,
+                 weak_factory_.GetWeakPtr(), observer));
 }
 
 void UINetworkQualityEstimatorService::RemoveEffectiveConnectionTypeObserver(
     net::NetworkQualityEstimator::EffectiveConnectionTypeObserver* observer) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   effective_connection_type_observer_list_.RemoveObserver(observer);
 }
 
 void UINetworkQualityEstimatorService::SetEffectiveConnectionTypeForTesting(
     net::EffectiveConnectionType type) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   EffectiveConnectionTypeChanged(type);
 }
 
 net::EffectiveConnectionType
 UINetworkQualityEstimatorService::GetEffectiveConnectionType() const {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   return type_;
 }
 
 void UINetworkQualityEstimatorService::ClearPrefs() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   if (!prefs_manager_)
     return;
   prefs_manager_->ClearPrefs();
 }
 
+void UINetworkQualityEstimatorService::
+    NotifyEffectiveConnectionTypeObserverIfPresent(
+        net::NetworkQualityEstimator::EffectiveConnectionTypeObserver* observer)
+        const {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  if (!effective_connection_type_observer_list_.HasObserver(observer))
+    return;
+  if (type_ == net::EFFECTIVE_CONNECTION_TYPE_UNKNOWN)
+    return;
+  observer->OnEffectiveConnectionTypeChanged(type_);
+}
+
 // static
 void UINetworkQualityEstimatorService::RegisterProfilePrefs(
     PrefRegistrySimple* registry) {
   registry->RegisterDictionaryPref(prefs::kNetworkQualities,
                                    PrefRegistry::LOSSY_PREF);
 }
 
 std::map<net::nqe::internal::NetworkID,
          net::nqe::internal::CachedNetworkQuality>
 UINetworkQualityEstimatorService::ForceReadPrefsForTesting() const {
   if (!prefs_manager_) {
     return std::map<net::nqe::internal::NetworkID,
                     net::nqe::internal::CachedNetworkQuality>();
   }
   return prefs_manager_->ForceReadPrefsForTesting();
 }