Prevent navigations within fullscreen webapps from being intercepted.

chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java

Index: chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
index b4b153f4f2ee27d13baebec355283de222136ae1..41033b6d850b8574116e98422977e2688afd2c87 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/externalnav/ExternalNavigationDelegateImpl.java
@@ -41,6 +41,7 @@ import org.chromium.chrome.browser.document.ChromeLauncherActivity;
 import org.chromium.chrome.browser.externalnav.ExternalNavigationHandler.OverrideUrlLoadingResult;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.util.UrlUtilities;
+import org.chromium.chrome.browser.webapps.WebappActivity;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.common.Referrer;
 import org.chromium.ui.base.PageTransition;
@@ -240,6 +241,16 @@ public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegat
     }
 
     @Override
+    public boolean isWithinCurrentWebappScope(String url) {
+        Context context = getAvailableContext();
+        if (context instanceof WebappActivity) {
+            String scope = ((WebappActivity) context).getWebappScope();
+            return url.startsWith(scope);
+        }
+        return false;
+    }
+
+    @Override
     public int countSpecializedHandlers(List<ResolveInfo> infos) {
         return getSpecializedHandlersWithFilter(infos, null).size();
     }