Add histograms for data usage

chrome/browser/android/data_usage/external_data_use_observer_bridge.cc

 // Copyright 2015 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/android/data_usage/external_data_use_observer_bridge.h"
 
 #include <vector>
 
 #include "base/android/context_utils.h"
 #include "base/android/jni_string.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/time/time.h"
 #include "chrome/browser/android/data_usage/data_use_tab_model.h"
 #include "chrome/browser/android/data_usage/external_data_use_observer.h"
 #include "components/variations/variations_associated_data.h"
 #include "content/public/browser/browser_thread.h"
 #include "jni/ExternalDataUseObserver_jni.h"
 
 using base::android::ConvertUTF8ToJavaString;
 
@@ skipping 51 matching lines @@
       env, base::android::GetApplicationContext(),
       reinterpret_cast<intptr_t>(this)));
   DCHECK(!j_external_data_use_observer_.is_null());
 
   Java_ExternalDataUseObserver_setControlAppPackageName(
       env, j_external_data_use_observer_.obj(),
       ConvertUTF8ToJavaString(env, GetControlAppPackageName()).obj());
   FetchMatchingRules();
 }
 
-void ExternalDataUseObserverBridge::FetchMatchingRules() const {
+void ExternalDataUseObserverBridge::FetchMatchingRules() {
   DCHECK(thread_checker_.CalledOnValidThread());
+  if (matching_rules_first_fetch_time_.is_null())

[tbansal1, 2016/01/14 06:59:55]

make it a const variable, and set it in the construtor? Then, we will know how
much time it takes from ~start of chrome to first fetch?

[Raj, 2016/01/15 06:23:24]

Done.

+    matching_rules_first_fetch_time_ = base::TimeTicks::Now();
 
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_ExternalDataUseObserver_fetchMatchingRules(
       env, j_external_data_use_observer_.obj());
 }
 
 void ExternalDataUseObserverBridge::FetchMatchingRulesDone(
     JNIEnv* env,
     const base::android::JavaParamRef<jobject>& obj,
     const base::android::JavaParamRef<jobjectArray>& app_package_name,
     const base::android::JavaParamRef<jobjectArray>& domain_path_regex,
     const base::android::JavaParamRef<jobjectArray>& label) {
   DCHECK(thread_checker_.CalledOnValidThread());
+  DCHECK(!matching_rules_first_fetch_time_.is_null());
 
   // Convert to native objects.
   std::vector<std::string> app_package_name_native;
   std::vector<std::string> domain_path_regex_native;
   std::vector<std::string> label_native;
 
   if (app_package_name && domain_path_regex && label) {
     base::android::AppendJavaStringArrayToStringVector(
         env, app_package_name, &app_package_name_native);
     base::android::AppendJavaStringArrayToStringVector(
         env, domain_path_regex, &domain_path_regex_native);
     base::android::AppendJavaStringArrayToStringVector(env, label,
                                                        &label_native);
   }
 
   DCHECK_EQ(app_package_name_native.size(), domain_path_regex_native.size());
   DCHECK_EQ(app_package_name_native.size(), label_native.size());
 
   if (!data_use_tab_model_)
     return;
 
+  UMA_HISTOGRAM_TIMES(
+      "DataUsage.Perf.MatchingRuleFetchDuration",
+      base::TimeTicks::Now() - matching_rules_first_fetch_time_);

[tbansal1, 2016/01/14 06:59:55]

How do we know this is the first fetch? Seems like this will get recorded every
15 minutes.

[Raj, 2016/01/15 06:23:24]

Fixed

+
   data_use_tab_model_->RegisterURLRegexes(
       app_package_name_native, domain_path_regex_native, label_native);
 }
 
 void ExternalDataUseObserverBridge::ReportDataUse(
     const std::string& label,
     net::NetworkChangeNotifier::ConnectionType connection_type,
     const std::string& mcc_mnc,
     const base::Time& start_time,
     const base::Time& end_time,
@@ skipping 34 matching lines @@
   data_use_tab_model_->OnControlAppInstalled();
 }
 
 bool RegisterExternalDataUseObserver(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 }  // namespace android
 
 }  // namespace chrome