Let chrome_prefs handle Preferences initialization from master_preferences.

chrome/browser/first_run/first_run_browsertest.cc

Index: chrome/browser/first_run/first_run_browsertest.cc
diff --git a/chrome/browser/first_run/first_run_browsertest.cc b/chrome/browser/first_run/first_run_browsertest.cc
index bdcf1f5e5d7daf644db6637ce6e8f435f4eb915b..a4fea6326e43f7e3dfd9d7e2ea8cd84ef54ff293 100644
--- a/chrome/browser/first_run/first_run_browsertest.cc
+++ b/chrome/browser/first_run/first_run_browsertest.cc
@@ -20,7 +20,9 @@
 #include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "chrome/test/base/ui_test_utils.h"
+#include "components/user_prefs/user_prefs.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_switches.h"
 #include "content/public/test/test_launcher.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -229,4 +231,40 @@ IN_PROC_BROWSER_TEST_F(FirstRunMasterPrefsImportNothing,
   EXPECT_EQ(1, tab->GetMaxPageID());
 }
 
+// Test first run with some tracked preferences.
+extern const char kWithTrackedPrefs[] =
+    "{\n"
+    "  \"homepage\": \"test.com\",\n"

[erikwright (departed), 2014/02/04 20:55:28]

use example.com

[gab, 2014/02/04 22:32:11]

Done.

+    "  \"homepage_is_newtabpage\": false\n"
+    "}\n";
+// A test fixture which will run with in a first run scenario with

[erikwright (departed), 2014/02/04 20:55:28]

with in -> in

[erikwright (departed), 2014/02/04 20:55:28]

which -> that

[gab, 2014/02/04 22:32:11]

Done.

[gab, 2014/02/04 22:32:11]

Done.

+// master_preferences set to kWithTrackedPrefs. Parametrizable on the

[erikwright (departed), 2014/02/04 20:55:28]

parameterizable

[gab, 2014/02/04 22:32:11]

Done.

+// SettingsEnforcement experiment to be forced.
+class FirstRunMasterPrefsWithTrackedPreferences
+    : public FirstRunMasterPrefsBrowserTestT<kWithTrackedPrefs>,
+      public testing::WithParamInterface<std::string> {
+ public:
+  virtual void SetUpCommandLine(CommandLine* command_line) OVERRIDE {
+    FirstRunMasterPrefsBrowserTestT::SetUpCommandLine(command_line);
+    const std::string force_settings_enforcement_trial(
+        "SettingsEnforcement/" + GetParam() + "/");
+    command_line->AppendSwitchASCII(switches::kForceFieldTrials,

[erikwright (departed), 2014/02/04 20:55:28]

I'd just break after (, indent by 4 spaces, and inline
force_settings_enforcement_trial

[gab, 2014/02/04 22:32:11]

Done.

+                                    force_settings_enforcement_trial);
+  }
+};

[erikwright (departed), 2014/02/04 20:55:28]

blank line after };

[gab, 2014/02/04 22:32:11]

Done.

+IN_PROC_BROWSER_TEST_P(FirstRunMasterPrefsWithTrackedPreferences,
+                       TrackedPreferencesSurviveFirstRun) {
+  const PrefService* user_prefs = browser()->profile()->GetPrefs();
+  std::string tmp;

[erikwright (departed), 2014/02/04 20:55:28]

tmp is unused

[gab, 2014/02/04 22:32:11]

Oops, got too used to the DictionaryValue::Get interface :) -- turns out
PrefService doesn't need an out-param for its getters!

+  EXPECT_EQ("test.com", user_prefs->GetString(prefs::kHomePage));
+  EXPECT_FALSE(user_prefs->GetBoolean(prefs::kHomePageIsNewTabPage));

[erikwright (departed), 2014/02/04 20:55:28]

Can you add a test that the default is true, or something?

[gab, 2014/02/04 22:32:11]

Done.

+}
+
+INSTANTIATE_TEST_CASE_P(FirstRunMasterPrefsWithTrackedPreferencesInstance,
+                        FirstRunMasterPrefsWithTrackedPreferences,
+                        testing::Values("no_enforcement",
+                                        "enforce",
+                                        "enforce_no_seeding",
+                                        "enforce_no_seeding_no_migration"));
+
 #endif  // !defined(OS_CHROMEOS)