Install platform apps into a separate data directory

chrome/app/chrome_main_app_mode_mac.mm

Index: chrome/app/chrome_main_app_mode_mac.mm
diff --git a/chrome/app/chrome_main_app_mode_mac.mm b/chrome/app/chrome_main_app_mode_mac.mm
index 2c1789781f669b132377dff90dc2f400046d8886..34ea0205b6a51c4b69ae43de23e5a1ca61e3d726 100644
--- a/chrome/app/chrome_main_app_mode_mac.mm
+++ b/chrome/app/chrome_main_app_mode_mac.mm
@@ -48,9 +48,10 @@ int ChromeAppModeStart(const app_mode::ChromeAppModeInfo* info) {
   RAW_CHECK(info->app_mode_url.size());
   std::string argv1(std::string("--app-id=") + info->app_mode_id);
   RAW_CHECK(info->app_mode_id.size());
-  //std::string argv2(std::string("--user-data-dir=/tmp/") + info->app_mode_id);
+  std::string argv2(
+      std::string("--user-data-dir=") + info->user_data_dir.value());
   char* argv[] = { info->argv[0],
-                   const_cast<char*>(argv1.c_str()) /*,
-                   const_cast<char*>(argv2.c_str()) };*/ };
+                   const_cast<char*>(argv1.c_str()),
+                   const_cast<char*>(argv2.c_str()) };
   return ChromeMain(static_cast<int>(arraysize(argv)), argv);
 }