[Mac] Add interactive App Shim test.

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 202221732bc6c4995b2de55caafa107cb3eb423c..4d686dafeeebb9c08b8cea6a1fb11dc7864d4206 100644
--- a/chrome/common/mac/app_mode_common.h
+++ b/chrome/common/mac/app_mode_common.h
@@ -37,6 +37,10 @@ extern const char kAppListModeId[];
 // launch_now = false. This associates the shim without launching the app.
 extern const char kLaunchedByChromeProcessId[];
 
+// Indicates to the shim that it was launched for a test, so don't attempt to
+// launch Chrome.
+extern const char kLaunchedForTest[];
+
 // Path to an app shim bundle. Indicates to Chrome that this shim attempted to
 // launch but failed.
 extern const char kAppShimError[];