Allow user data dir to be specified in the environment.

chrome/app/chrome_main_delegate.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/app/chrome_main_delegate.h"
 
 #include "base/command_line.h"
+#include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/lazy_instance.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/statistics_recorder.h"
 #include "base/metrics/stats_counters.h"
 #include "base/path_service.h"
 #include "base/process/memory.h"
 #include "base/process/process_handle.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 583 matching lines @@
   InitMacCrashReporter(command_line, process_type);
 #endif
 
 #if defined(OS_WIN)
   child_process_logging::Init();
 #endif
 
   // Notice a user data directory override if any
   base::FilePath user_data_dir =
       command_line.GetSwitchValuePath(switches::kUserDataDir);
+#if defined(OS_LINUX)
+  // On Linux, Chrome does not support running multiple copies under different
+  // DISPLAYs, so the profile directory can be specified in the environment to
+  // support the virtual desktop use-case.
+  if (user_data_dir.empty()) {
+    std::string user_data_dir_string;
+    scoped_ptr<base::Environment> environment(base::Environment::Create());
+    if (environment->GetVar("CHROME_USER_DATA_DIR", &user_data_dir_string) &&
+        IsStringUTF8(user_data_dir_string)) {
+      user_data_dir = base::FilePath::FromUTF8Unsafe(user_data_dir_string);
+    }
+  }
+#endif
 #if defined(OS_MACOSX) || defined(OS_WIN)
   policy::path_parser::CheckUserDataDirPolicy(&user_data_dir);
 #endif
   if (!user_data_dir.empty()) {
     CHECK(PathService::OverrideAndCreateIfNeeded(
         chrome::DIR_USER_DATA,
         user_data_dir,
         chrome::ProcessNeedsProfileDir(process_type)));
   }
 
@@ skipping 244 matching lines @@
 }
 
 content::ContentUtilityClient*
 ChromeMainDelegate::CreateContentUtilityClient() {
 #if defined(CHROME_MULTIPLE_DLL_BROWSER)
   return NULL;
 #else
   return &g_chrome_content_utility_client.Get();
 #endif
 }