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

chrome/browser/about_flags_unittest.cc

Index: chrome/browser/about_flags_unittest.cc
diff --git a/chrome/browser/about_flags_unittest.cc b/chrome/browser/about_flags_unittest.cc
index 0cb9fa78835f36a552cf7fe0ffe1ed07170e7871..c8c426969ca89beee380cbd43187c547b3650480 100644
--- a/chrome/browser/about_flags_unittest.cc
+++ b/chrome/browser/about_flags_unittest.cc
@@ -233,22 +233,45 @@ TEST_F(AboutFlagsTest, ConvertFlagsToSwitches) {
   EXPECT_FALSE(command_line2.HasSwitch(switches::kFlagSwitchesEnd));
 }
 
+CommandLine::StringType CreateSwitch(const std::string& value) {
+#if defined(OS_WIN)
+  return ASCIIToUTF16(value);
+#else
+  return value;
+#endif
+}
+
 TEST_F(AboutFlagsTest, CompareSwitchesToCurrentCommandLine) {
   SetExperimentEnabled(&flags_storage_, kFlags1, true);
 
+  const std::string kDoubleDash("--");
+
   CommandLine command_line(CommandLine::NO_PROGRAM);
   command_line.AppendSwitch("foo");
 
   CommandLine new_command_line(CommandLine::NO_PROGRAM);
   ConvertFlagsToSwitches(&flags_storage_, &new_command_line, kAddSentinels);
 
-  EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(new_command_line,
-                                                        command_line));
+  EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(
+      new_command_line, command_line, NULL));
+  {
+    std::set<CommandLine::StringType> difference;
+    EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(
+        new_command_line, command_line, &difference));
+    EXPECT_EQ(1U, difference.size());
+    EXPECT_EQ(1U, difference.count(CreateSwitch(kDoubleDash + kSwitch1)));
+  }
 
   ConvertFlagsToSwitches(&flags_storage_, &command_line, kAddSentinels);
 
-  EXPECT_TRUE(AreSwitchesIdenticalToCurrentCommandLine(new_command_line,
-                                                       command_line));
+  EXPECT_TRUE(AreSwitchesIdenticalToCurrentCommandLine(
+      new_command_line, command_line, NULL));
+  {
+    std::set<CommandLine::StringType> difference;
+    EXPECT_TRUE(AreSwitchesIdenticalToCurrentCommandLine(
+        new_command_line, command_line, &difference));
+    EXPECT_TRUE(difference.empty());
+  }
 
   // Now both have flags but different.
   SetExperimentEnabled(&flags_storage_, kFlags1, false);
@@ -257,8 +280,18 @@ TEST_F(AboutFlagsTest, CompareSwitchesToCurrentCommandLine) {
   CommandLine another_command_line(CommandLine::NO_PROGRAM);
   ConvertFlagsToSwitches(&flags_storage_, &another_command_line, kAddSentinels);
 
-  EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(new_command_line,
-                                                        another_command_line));
+  EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(
+      new_command_line, another_command_line, NULL));
+  {
+    std::set<CommandLine::StringType> difference;
+    EXPECT_FALSE(AreSwitchesIdenticalToCurrentCommandLine(
+        new_command_line, another_command_line, &difference));
+    EXPECT_EQ(2U, difference.size());
+    EXPECT_EQ(1U, difference.count(CreateSwitch(kDoubleDash + kSwitch1)));
+    EXPECT_EQ(1U,
+              difference.count(CreateSwitch(kDoubleDash + kSwitch2 + "=" +
+                                            kValueForSwitch2)));
+  }
 }
 
 TEST_F(AboutFlagsTest, RemoveFlagSwitches) {