Collect UMA statistics on which chrome://flags lead to chrome restart on ChromeOS.

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 2126 matching lines @@
 
 void ConvertFlagsToSwitches(FlagsStorage* flags_storage,
                             CommandLine* command_line,
                             SentinelsMode sentinels) {
   FlagsState::GetInstance()->ConvertFlagsToSwitches(flags_storage,
                                                     command_line,
                                                     sentinels);
 }
 
 bool AreSwitchesIdenticalToCurrentCommandLine(
-    const CommandLine& new_cmdline, const CommandLine& active_cmdline) {
+    const CommandLine& new_cmdline,
+    const CommandLine& active_cmdline,
+    std::set<CommandLine::StringType>* out_difference) {
   std::set<CommandLine::StringType> new_flags =
       ExtractFlagsFromCommandLine(new_cmdline);
   std::set<CommandLine::StringType> active_flags =
       ExtractFlagsFromCommandLine(active_cmdline);
 
+  bool result = true;
   // Needed because std::equal doesn't check if the 2nd set is empty.
-  if (new_flags.size() != active_flags.size())
-    return false;
+  if (new_flags.size() != active_flags.size()) {
+    result = false;
+  } else {
+    std::equal(new_flags.begin(), new_flags.end(), active_flags.begin());

[Nikita (slow), 2014/06/19 17:08:07]

result = 

[Alexander Alekseev, 2014/06/19 18:17:47]

Done.

+  }
 
-  return std::equal(new_flags.begin(), new_flags.end(), active_flags.begin());
+  if (out_difference && !result) {
+    std::set_symmetric_difference(
+        new_flags.begin(),
+        new_flags.end(),
+        active_flags.begin(),
+        active_flags.end(),
+        std::inserter(*out_difference, out_difference->begin()));
+  }
+
+  return result;
 }
 
 void GetFlagsExperimentsData(FlagsStorage* flags_storage,
                              FlagAccess access,
                              base::ListValue* supported_experiments,
                              base::ListValue* unsupported_experiments) {
   std::set<std::string> enabled_experiments;
   GetSanitizedEnabledFlags(flags_storage, &enabled_experiments);
 
   int current_platform = GetCurrentPlatform();
@@ skipping 286 matching lines @@
 }
 
 const Experiment* GetExperiments(size_t* count) {
   *count = num_experiments;
   return experiments;
 }
 
 }  // namespace testing
 
 }  // namespace about_flags