Support variations_seed parameter in MasterPrefs.

chrome/browser/chrome_browser_main.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/chrome_browser_main.h"
 
 #if defined(TOOLKIT_GTK)
 #include <gtk/gtk.h>
 #endif
 
@@ skipping 792 matching lines @@
   // creatable, for example; on Windows in code below we bring up a
   // dialog prompting the user to pick a different directory.
   // However, ProcessSingleton needs a real user_data_dir on Mac/Linux,
   // so it's better to fail here than fail mysteriously elsewhere.
   CHECK(PathService::Get(chrome::DIR_USER_DATA, &user_data_dir_))
       << "Must be able to get user data directory!";
 #endif
 
   // Whether this is First Run. |do_first_run_tasks_| should be prefered to this
   // unless the desire is actually to know whether this is really First Run
   // (i.e., even if --no-first-run is passed).

[gab, 2013/02/11 23:44:01]

ref.

   bool is_first_run = false;
   // Android's first run is done in Java instead of native.
 #if !defined(OS_ANDROID)
 
   process_singleton_.reset(new ProcessSingleton(user_data_dir_));
   // Ensure ProcessSingleton won't process messages too early. It will be
   // unlocked in PostBrowserStart().
   process_singleton_->Lock(NULL);
 
   bool force_first_run =
@@ skipping 121 matching lines @@
                            !parsed_command_line().HasSwitch(switches::kApp) &&
                            !parsed_command_line().HasSwitch(switches::kAppId));
 
     if (do_first_run_tasks_) {
       AddFirstRunNewTabs(browser_creator_.get(), master_prefs_->new_tabs);
     } else if (parsed_command_line().HasSwitch(switches::kNoFirstRun)) {
       // Create the First Run beacon anyways if --no-first-run was passed on the
       // command line.
       first_run::CreateSentinel();
     }
+
+    // Store the initial VariationsService seed in local state, if it exists in
+    // master prefs.
+    if (!master_prefs_->variations_seed.empty()) {

[gab, 2013/02/11 23:44:01]

See referenced comment above, this should probably be gated on
|do_first_run_tasks_| instead of |is_first_run|.

[Alexei Svitkine (slow), 2013/02/12 00:11:31]

Done. Can you explain the difference between the two? In what real world
scenarios would doing it in do_first_run_tasks_ not be the same as doing it
here?

[gab, 2013/02/12 00:31:06]

No difference in the real world; using |do_first_run_tasks_| will however
prevent this from happening in a situation where the First Run sentinel is
absent (i.e., it "is" first run as far as the browser is concerned), but
--no-first-run is on the command-line; this mainly makes sure that tests do not
end up running first run code.

I tried to unify the two variables in December IIRC as part of fixing master
preferences bugs for the fixit, but there was one thing holding me off (I
forget, something that needs to be initialized no matter what I think).

+      local_state_->SetString(prefs::kVariationsSeed,
+                              master_prefs_->variations_seed);
+      // Set the variation seed date to the current system time. If the user's
+      // clock is incorrect, this may cause some field trial expiry checks to
+      // not do the right thing until the next seed update from the server, when
+      // this value will be updated.
+      local_state_->SetInt64(prefs::kVariationsSeedDate,
+                             base::Time::Now().ToInternalValue());
+    }
   }
 #endif
 
   // TODO(viettrungluu): why don't we run this earlier?
   if (!parsed_command_line().HasSwitch(switches::kNoErrorDialogs))
     WarnAboutMinimumSystemRequirements();
 
 #if defined(OS_LINUX) || defined(OS_OPENBSD) || defined(OS_MACOSX)
   // Set the product channel for crash reports.
   child_process_logging::SetChannel(
@@ skipping 818 matching lines @@
     if (base::win::GetVersion() <= base::win::VERSION_XP)
       uma_name += "_XP";
 
     uma_name += "_PreRead_";
     uma_name += pre_read_percentage;
     AddPreReadHistogramTime(uma_name.c_str(), time);
   }
 #endif
 #endif
 }