Open the notification URL (not the web app start_url) when deep-linking into standalone mode.

chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java b/chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java
index a9729f008424433ff109df83195bf15156467842..0bf4a074cb812f80e7b2e0c378f5084c55e8b74b 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ServiceTabLauncher.java
@@ -105,6 +105,9 @@ public class ServiceTabLauncher {
 
                         @Override
                         protected final void onPostExecute(Intent intent) {
+                            // Replace the web app URL with the URL from the notification. This is
+                            // within the webapp's scope, so it is valid.
+                            intent.putExtra(ShortcutHelper.EXTRA_URL, url);
                             intent.putExtra(ShortcutHelper.EXTRA_SOURCE,
                                     ShortcutSource.NOTIFICATION);
                             tabDelegate.createNewStandaloneFrame(intent);