NQE: Always read prefs in cronet

components/cronet/android/cronet_url_request_context_adapter.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 "components/cronet/android/cronet_url_request_context_adapter.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 187 matching lines @@
 
     base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
         FROM_HERE,
         base::Bind(
             &NetworkQualitiesPrefDelegateImpl::SchedulePendingLossyWrites,
             weak_ptr_factory_.GetWeakPtr()),
         base::TimeDelta::FromSeconds(kUpdatePrefsDelaySeconds));
   }
   std::unique_ptr<base::DictionaryValue> GetDictionaryValue() override {
     DCHECK(thread_checker_.CalledOnValidThread());
-    // TODO(tbansal): Add logic to read prefs if the embedder has enabled cached
-    // estimates.
-    return base::WrapUnique(new base::DictionaryValue());
+    UMA_HISTOGRAM_EXACT_LINEAR("NQE.Prefs.ReadCount", 1, 2);
+    return pref_service_->GetDictionary(kNetworkQualities)->CreateDeepCopy();

[xunjieli, 2017/02/07 21:05:59]

Does |pref_service_| return empty DictionaryValue if prefs are not yet loaded?

[tbansal1, 2017/02/09 17:36:26]

Yes, it will return an empty map. 
Prefs are read synchronously in Cronet and in the initial profile in Chrome, so
that should not be a problem.

   }
 
  private:
   // Schedules the writing of the lossy prefs.
   void SchedulePendingLossyWrites() {
     DCHECK(thread_checker_.CalledOnValidThread());
+    UMA_HISTOGRAM_EXACT_LINEAR("NQE.Prefs.WriteCount", 1, 2);
     pref_service_->SchedulePendingLossyWrites();
     lossy_prefs_writing_task_posted_ = false;
   }
 
   PrefService* pref_service_;
 
   // True if the task that schedules the writing of the lossy prefs has been
   // posted.
   bool lossy_prefs_writing_task_posted_;
 
@@ skipping 963 matching lines @@
     JNIEnv* env,
     const JavaParamRef<jclass>& jcaller) {
   base::StatisticsRecorder::Initialize();
   std::vector<uint8_t> data;
   if (!HistogramManager::GetInstance()->GetDeltas(&data))
     return ScopedJavaLocalRef<jbyteArray>();
   return base::android::ToJavaByteArray(env, &data[0], data.size());
 }
 
 }  // namespace cronet