session_manager: Create ChromeSessionManager early

chrome/browser/browser_process_platform_part_chromeos.cc

Index: chrome/browser/browser_process_platform_part_chromeos.cc
diff --git a/chrome/browser/browser_process_platform_part_chromeos.cc b/chrome/browser/browser_process_platform_part_chromeos.cc
index 0369f1444a951e3dc2fd006bb1fdd10421814e80..804368d84c433de6fbcae5da731765acbaf4b5e1 100644
--- a/chrome/browser/browser_process_platform_part_chromeos.cc
+++ b/chrome/browser/browser_process_platform_part_chromeos.cc
@@ -4,7 +4,6 @@
 
 #include "chrome/browser/browser_process_platform_part_chromeos.h"
 
-#include "base/command_line.h"
 #include "base/logging.h"
 #include "base/time/default_tick_clock.h"
 #include "base/time/tick_clock.h"
@@ -23,7 +22,6 @@
 #include "chrome/browser/chromeos/system/timezone_util.h"
 #include "chrome/browser/lifetime/keep_alive_types.h"
 #include "chrome/browser/lifetime/scoped_keep_alive.h"
-#include "chrome/browser/profiles/profile.h"
 #include "chrome/common/chrome_switches.h"
 #include "chromeos/geolocation/simple_geolocation_provider.h"
 #include "chromeos/timezone/timezone_resolver.h"
@@ -74,24 +72,15 @@ void BrowserProcessPlatformPart::ShutdownDeviceDisablingManager() {
   device_disabling_manager_delegate_.reset();
 }
 
-void BrowserProcessPlatformPart::InitializeSessionManager(
-    const base::CommandLine& parsed_command_line,
-    Profile* profile,
-    bool is_running_test) {
+void BrowserProcessPlatformPart::CreateSessionManager() {
   DCHECK(!session_manager_);
-  session_manager_ = chromeos::ChromeSessionManager::CreateSessionManager(
-      parsed_command_line, profile, is_running_test);
+  session_manager_.reset(new chromeos::ChromeSessionManager);
 }
 
 void BrowserProcessPlatformPart::ShutdownSessionManager() {
   session_manager_.reset();
 }
 
-session_manager::SessionManager* BrowserProcessPlatformPart::SessionManager() {
-  DCHECK(CalledOnValidThread());

[achuithb, 2016/10/27 19:12:45]

Is this DCHECK no longer important?

[xiyuan, 2016/10/27 21:10:43]

I am not sure why we need it in first place. Original CL
(https://codereview.chromium.org/363613004) is created by following the existing
paradigm without justification. I feel it is redundant since most chrome code
assumes running on UI thread. And other accessors (e.g.
automatic_reboot_manager(), user_manager() etc) do not check thread.

I think this should be okay. And if we do need to guard this, we can make
SessionManager NonThreadSafe and check in its methods.

WDYT?

[achuithb, 2016/10/27 21:18:52]

Acknowledged.

-  return session_manager_.get();
-}
-
 void BrowserProcessPlatformPart::RegisterKeepAlive() {
   DCHECK(!keep_alive_);
   keep_alive_.reset(