Put app shim IPC socket in a temporary directory. (Mac)

chrome/common/mac/app_mode_common.h

Index: chrome/common/mac/app_mode_common.h
diff --git a/chrome/common/mac/app_mode_common.h b/chrome/common/mac/app_mode_common.h
index de82e2450d33b2b74646edde0f16e0ef937ed86c..858b60d7eea6f11ba8dd64223d9bbad6b0e71c7a 100644
--- a/chrome/common/mac/app_mode_common.h
+++ b/chrome/common/mac/app_mode_common.h
@@ -127,6 +127,11 @@ struct ChromeAppModeInfo {
   base::FilePath profile_dir;
 };
 
+// Due to kernel API restraints on the length of the path to a socket, we
+// cannot use a socket under the user data dir. GetShortSocketPath returns a
+// path under /tmp constructed from a hash of the user data dir.
+base::FilePath GetShortSocketPath(const base::FilePath& user_data_dir);
+
 }  // namespace app_mode
 
 #endif  // CHROME_COMMON_MAC_APP_MODE_COMMON_H_