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

chrome/browser/about_flags.cc

Index: chrome/browser/about_flags.cc
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 7577556a0b3e3a97ca013d70cf3a88c938e8c25c..3f25c3a918404c43bc116e91e5ba9a486a3b2049 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -2144,17 +2144,32 @@ void ConvertFlagsToSwitches(FlagsStorage* flags_storage,
 }
 
 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,