Switch platform apps from a declarative launch container to handling an onLaunched event.

chrome/browser/extensions/api/runtime/runtime_api.h

Index: chrome/browser/extensions/api/runtime/runtime_api.h
diff --git a/chrome/browser/extensions/api/runtime/runtime_api.h b/chrome/browser/extensions/api/runtime/runtime_api.h
index 3db57647118a42554c47c6cfc801ec01741c723d..66c7fd7d4988d203bb04e67350c0481dc912f422 100644
--- a/chrome/browser/extensions/api/runtime/runtime_api.h
+++ b/chrome/browser/extensions/api/runtime/runtime_api.h
@@ -16,6 +16,10 @@ class RuntimeEventRouter {
   // Dispatches the onInstalled event to the given extension.
   static void DispatchOnInstalledEvent(Profile* profile,
                                        const Extension* extension);
+
+  // Dispatches the onLaunched event to the given app.
+  static void DispatchOnLaunchedEvent(Profile* profile,
+                                      const Extension* extension);
 };
 
 }  // namespace extensions