Log base::Features in Launch.FlagsAtStartup

chrome/browser/about_flags.cc

 // Copyright (c) 2012 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/about_flags.h"
 
 #include <iterator>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 2209 matching lines @@
   FlagsStateSingleton::GetFlagsState()->RemoveFlagsSwitches(switch_list);
 }
 
 void ResetAllFlags(flags_ui::FlagsStorage* flags_storage) {
   FlagsStateSingleton::GetFlagsState()->ResetAllFlags(flags_storage);
 }
 
 void RecordUMAStatistics(flags_ui::FlagsStorage* flags_storage) {
   const std::set<std::string> switches =
       FlagsStateSingleton::GetFlagsState()->GetSwitchesFromFlags(flags_storage);
-  ReportAboutFlagsHistogram("Launch.FlagsAtStartup", switches);
+  const std::set<std::string> features =
+      FlagsStateSingleton::GetFlagsState()->GetFeaturesFromFlags(flags_storage);
+  ReportAboutFlagsHistogram("Launch.FlagsAtStartup", switches, features);
 }
 
 base::HistogramBase::Sample GetSwitchUMAId(const std::string& switch_name) {
   return static_cast<base::HistogramBase::Sample>(
       base::HashMetricName(switch_name));
 }
 
-void ReportAboutFlagsHistogram(const std::string& uma_histogram_name,
-                               const std::set<std::string>& flags) {
-  for (const std::string& flag : flags) {
+void ReportAboutFlagsHistogram(
+    const std::string& uma_histogram_name,
+    const std::set<std::string>& switches,
+    const std::set<std::string>& features) {
+  ReportAboutFlagsHistogramSwitches(uma_histogram_name, switches);
+  ReportAboutFlagsHistogramFeatures(uma_histogram_name, features);
+}
+
+void ReportAboutFlagsHistogramSwitches(const std::string& uma_histogram_name,
+                                       const std::set<std::string>& switches) {
+  for (const std::string& flag : switches) {
     int uma_id = about_flags::testing::kBadSwitchFormatHistogramId;
     if (base::StartsWith(flag, "--", base::CompareCase::SENSITIVE)) {
       // Skip '--' before switch name.
       std::string switch_name(flag.substr(2));
 
       // Kill value, if any.
       const size_t value_pos = switch_name.find('=');
       if (value_pos != std::string::npos)
         switch_name.resize(value_pos);
 
       uma_id = GetSwitchUMAId(switch_name);
     } else {
       NOTREACHED() << "ReportAboutFlagsHistogram(): flag '" << flag
                    << "' has incorrect format.";
     }
     DVLOG(1) << "ReportAboutFlagsHistogram(): histogram='" << uma_histogram_name
              << "' '" << flag << "', uma_id=" << uma_id;
 
     // Sparse histogram macro does not cache the histogram, so it's safe
     // to use macro with non-static histogram name here.
     UMA_HISTOGRAM_SPARSE_SLOWLY(uma_histogram_name, uma_id);
   }
 }
 
+void ReportAboutFlagsHistogramFeatures(const std::string& uma_histogram_name,

[Alexei Svitkine (slow), 2016/09/16 15:52:38]

If this is not called from anywhere except this file, please move it into the
anonymous namespace at the top of the file. Also, please add a function comment
above it.

Same for the other function.

[lawrencewu, 2016/09/16 17:12:57]

Done.

+                                       const std::set<std::string>&features) {
+  for (const std::string& feature : features) {
+    int uma_id = about_flags::testing::kBadSwitchFormatHistogramId;
+
+    uma_id = GetSwitchUMAId(feature);
+    DVLOG(1) << "ReportAboutFlagsHistogram(): histogram='" << uma_histogram_name
+             << "' '" << feature << "', uma_id=" << uma_id;
+
+    // Sparse histogram macro does not cache the histogram, so it's safe
+    // to use macro with non-static histogram name here.
+    UMA_HISTOGRAM_SPARSE_SLOWLY(uma_histogram_name, uma_id);
+  }
+}
+
 namespace testing {
 
 const base::HistogramBase::Sample kBadSwitchFormatHistogramId = 0;
 
 const FeatureEntry* GetFeatureEntries(size_t* count) {
   *count = arraysize(kFeatureEntries);
   return kFeatureEntries;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags