NetworkQualityEstimator: Enable prefs writing by default

chrome/browser/net/nqe/ui_network_quality_estimator_service.cc

Index: chrome/browser/net/nqe/ui_network_quality_estimator_service.cc
diff --git a/chrome/browser/net/nqe/ui_network_quality_estimator_service.cc b/chrome/browser/net/nqe/ui_network_quality_estimator_service.cc
index d0aada131d3fd13aa17ae48a3d19c09dd4db8db3..09b3d3397c6d87d3cb83314c096bfd2b42565007 100644
--- a/chrome/browser/net/nqe/ui_network_quality_estimator_service.cc
+++ b/chrome/browser/net/nqe/ui_network_quality_estimator_service.cc
@@ -43,14 +43,20 @@ std::string GetStringValueForVariationParamWithDefaultValue(
 // trial.
 bool persistent_cache_writing_enabled() {
   return GetStringValueForVariationParamWithDefaultValue(
-             "persistent_cache_writing_enabled", "false") == "true";
+             "persistent_cache_writing_enabled", "true") == "true";
 }
 
 // Returns true if reading from the persistent cache has been enabled via field
 // trial.
 bool persistent_cache_reading_enabled() {
-  return GetStringValueForVariationParamWithDefaultValue(
-             "persistent_cache_reading_enabled", "false") == "true";
+  if (GetStringValueForVariationParamWithDefaultValue(
+          "persistent_cache_reading_enabled", "false") != "true") {
+    return false;
+  }
+  // If reading from prefs is enabled, then writing to prefs must be enabled
+  // too.
+  DCHECK(persistent_cache_writing_enabled());
+  return true;
 }
 
 // PrefDelegateImpl writes the provided dictionary value to the network quality
@@ -71,14 +77,14 @@ class PrefDelegateImpl
       return;
 
     pref_service_->Set(path_, value);
-    UMA_HISTOGRAM_COUNTS_1000("NQE.Prefs.WriteCount", 1);
+    UMA_HISTOGRAM_EXACT_LINEAR("NQE.Prefs.WriteCount", 1, 2);
   }
 
   std::unique_ptr<base::DictionaryValue> GetDictionaryValue() override {
     DCHECK(thread_checker_.CalledOnValidThread());
     if (!persistent_cache_reading_enabled())
       return base::WrapUnique(new base::DictionaryValue());
-    UMA_HISTOGRAM_COUNTS_1000("NQE.Prefs.ReadCount", 1);
+    UMA_HISTOGRAM_EXACT_LINEAR("NQE.Prefs.ReadCount", 1, 2);
     return pref_service_->GetDictionary(path_)->CreateDeepCopy();
   }