Use the shim bundle's user_data_dir instead of GetUserDataDirectoryForBrowserBundle.

apps/app_shim/chrome_main_app_mode_mac.mm

Index: apps/app_shim/chrome_main_app_mode_mac.mm
diff --git a/apps/app_shim/chrome_main_app_mode_mac.mm b/apps/app_shim/chrome_main_app_mode_mac.mm
index 2302b047b7e464779dc016a6d668ed2fa6e9de36..04fb49e7ac37b651d2f3e3b1b93df49f643a04d9 100644
--- a/apps/app_shim/chrome_main_app_mode_mac.mm
+++ b/apps/app_shim/chrome_main_app_mode_mac.mm
@@ -23,7 +23,6 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/threading/thread.h"
 #include "chrome/common/chrome_paths.h"
-#include "chrome/common/chrome_paths_internal.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/mac/app_mode_common.h"
 #include "ipc/ipc_channel_proxy.h"
@@ -97,18 +96,20 @@ AppShimController::AppShimController() : channel_(NULL),
 
 void AppShimController::Init() {
   DCHECK(g_io_thread);
-  NSString* chrome_bundle_path =
-      base::SysUTF8ToNSString(g_info->chrome_outer_bundle_path.value());
-  NSBundle* chrome_bundle = [NSBundle bundleWithPath:chrome_bundle_path];
-  base::FilePath user_data_dir;
-  if (!chrome::GetUserDataDirectoryForBrowserBundle(chrome_bundle,

[tapted, 2013/07/17 08:34:21]

I started wondering whether this approach was chosen because it gives a stronger
guarantee that "this" running chrome_main_app_mode_mac.mm process, and the
Chrome process it tries to connect to, will come from the same release.

E.g. if the IPC protocol changes between releases, does this change increase the
chance that it could find and connect to a Chrome talking a different language.

But I think that's actually not the case.

[jackhou1, 2013/07/30 07:34:34]

The Info.plist has Chrome's bundle id, which app_mode_loader uses to find the
framework bundle. So I think you're guaranteed to use the same version is if
there's only one app bundle with that id, and you don't share user_data_dirs
between different app bundles.

-                                                    &user_data_dir)) {
+  if (g_info->user_data_dir.empty()) {

[tapted, 2013/07/17 08:34:21]

Can a shim ever be created like this? Maybe just CHECK, and ditch the early
Close().

[jackhou1, 2013/07/30 07:34:34]

Done.

     Close();
     return;
   }
 
-  base::FilePath socket_path =
-      user_data_dir.Append(app_mode::kAppShimSocketName);
+  base::FilePath socket_path;
+  base::FilePath maybe_profile_dir =

[tapted, 2013/07/17 08:34:21]

Perhaps a helper function, which describes the logic here in some comments..

[jackhou1, 2013/07/30 07:34:34]

Since we're not changing the user_data_dir field, this logic is much simpler.

+      g_info->user_data_dir.DirName().DirName().BaseName();
+  if (maybe_profile_dir == g_info->profile_dir)

[tapted, 2013/07/17 08:34:21]

What happens if someone's Chrome user data dir is two levels below some random
folder called 'Default'?

[jackhou1, 2013/07/30 07:34:34]

Obsolete since we're leaving the user_data_dir unchanged for now.

+    socket_path = g_info->user_data_dir.DirName().DirName().DirName();
+  else
+    socket_path = g_info->user_data_dir;
+
+  socket_path = socket_path.Append(app_mode::kAppShimSocketName);
   IPC::ChannelHandle handle(socket_path.value());
   channel_ = new IPC::ChannelProxy(handle, IPC::Channel::MODE_NAMED_CLIENT,
       this, g_io_thread->message_loop_proxy().get());