Fixes intent chooser being shown incorrectly when going from HTTPS to HTTP for

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 9610a5e9793400a8b25155ec931f389b21b35cbe..63d63b005785d3209e4f5bdca601d5e90e7dc8e2 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
@@ -557,6 +557,8 @@ public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegat
 
     @Override
     public boolean isSerpReferrer(Tab tab) {
+        // TODO (thildebr): Investigate whether or not we can use getLastCommittedUrl() instead of
+        // the NavigationController.
         if (tab == null || tab.getWebContents() == null) return false;
 
         NavigationController nController = tab.getWebContents().getNavigationController();
@@ -596,6 +598,12 @@ public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegat
         return false;
     }
 
+    @Override
+    public String getPreviousUrl() {
+        if (mTab == null || mTab.getWebContents() == null) return null;
+        return mTab.getWebContents().getLastCommittedUrl();
+    }
+
     /**
      * Dispatches the intent through a proxy activity, so that startActivityForResult can be used
      * and the intent recipient can verify the caller.