If possible, use the PathService instead of the --user-data-dir flag directly

Some classes still using it directly are:
- cloud_print_proxy_process_browsertest.cc (it's not a browser test so it doesn't
call ChromeMainDelegate::PreSandboxStartup(), which sets up the PathService
to know about the user-data-dir

- in_process_browser_test.cc, which needs to set up the user-data-dir directory
before PreSandboxStartup() is called

- diagnostics_model and diagnostics_controller, which are used in
BasicStartupComplete(), which is called before PreSandboxStartup() where the
PathService is set up

- shell_integration_win.cc which has a function that's used in unit tests, which
don't call PreSandboxStartup()

- chrome/browser/shell_integration.cc is used differently on linux than on other
platforms, and on the former a desktop app shortcut uses a different command line
that that of Chrome's

- cloud_print/service/*, since it seems to be its own thing, and have a separate
user_data_dir

BUG=464616

Review URL: https://codereview.chromium.org/1010923002

Cr-Commit-Position: refs/heads/master@{#322697}

chrome/app/chrome_main_delegate.cc

@@ -345,10 +345,8 @@ void InitializeUserDataDir() {
 
   // On Windows, trailing separators leave Chrome in a bad state.
   // See crbug.com/464616.
-  if (user_data_dir.EndsWithSeparator()) {
+  if (user_data_dir.EndsWithSeparator())
     user_data_dir = user_data_dir.StripTrailingSeparators();
-    command_line->AppendSwitchPath(switches::kUserDataDir, user_data_dir);
-  }
 
   const bool specified_directory_was_invalid = !user_data_dir.empty() &&
       !PathService::OverrideAndCreateIfNeeded(chrome::DIR_USER_DATA,

chrome/installer/util/auto_launch_util.cc

@@ -185,12 +185,19 @@ void SetWillLaunchAtLogin(const base::FilePath& application_path,
 
       const base::CommandLine& command_line =
           *base::CommandLine::ForCurrentProcess();
+
+      // Propagate --user-data-dir if it was specified on the command line.
+      // Retrieve the value from the PathService since some sanitation may have
+      // taken place. There is no need to add it to the command line in the
+      // event that the dir was overridden by Group Policy since the GP override
+      // will be in force when Chrome is launched.
       if (command_line.HasSwitch(switches::kUserDataDir)) {
         cmd_line += ASCIIToUTF16(" --");
         cmd_line += ASCIIToUTF16(switches::kUserDataDir);
         cmd_line += ASCIIToUTF16("=\"");
-        cmd_line +=
-            command_line.GetSwitchValuePath(switches::kUserDataDir).value();
+        base::FilePath user_data_dir;
+        PathService::Get(chrome::DIR_USER_DATA, &user_data_dir);
+        cmd_line += user_data_dir.value();
         cmd_line += ASCIIToUTF16("\"");
       }
 

chrome/service/cloud_print/cloud_print_proxy.cc

@@ -34,6 +34,8 @@ void LaunchBrowserProcessWithSwitch(const std::string& switch_string) {
   }
   base::CommandLine cmd_line(exe_path);
 
+  // Propagate an explicit --user-data-dir value if one was given. The new
+  // browser process will pick up a policy override during initialization.
   const base::CommandLine& process_command_line =
       *base::CommandLine::ForCurrentProcess();
   base::FilePath user_data_dir =