Implement app launch changes for app runtime extension proposal.

extensions/common/constants.h

Index: extensions/common/constants.h
diff --git a/extensions/common/constants.h b/extensions/common/constants.h
index 185ab79d0146dd89d9de725daa9c9ea3c29e691e..e8ae77d6eeffe24fcd44715a5f733c9b06d8703a 100644
--- a/extensions/common/constants.h
+++ b/extensions/common/constants.h
@@ -131,10 +131,20 @@ enum AppLaunchSource {
   SOURCE_CHROME_INTERNAL,
   SOURCE_TEST,
   SOURCE_INSTALLED_NOTIFICATION,
+  SOURCE_ACTION,
 
   NUM_APP_LAUNCH_SOURCES
 };
 
+// Type of action to launch. Only applies if AppLaunchSource is set to
+// SOURCE_ACTION.
+enum class ActionType { NEW_NOTE };
+
+// Action-specific data to launch with.
+struct ActionData {
+  ActionType action_type;
+};
+
 // This enum is used for the launch type the user wants to use for an
 // application.
 // Do not remove items or re-order this enum as it is used in preferences