Disable external navigation for file downloads.

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.chrome.browser.externalnav;
 
 import android.Manifest.permission;
 import android.app.Activity;
 import android.content.Context;
 import android.content.DialogInterface;
 import android.content.DialogInterface.OnCancelListener;
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
 import android.net.Uri;
 import android.os.Build;
 import android.os.TransactionTooLargeException;
 import android.provider.Browser;
 import android.provider.Telephony;
 import android.support.v7.app.AlertDialog;
 import android.text.TextUtils;
 import android.util.Log;
+import android.webkit.MimeTypeMap;
 
 import org.chromium.base.ApplicationState;
 import org.chromium.base.ApplicationStatus;
 import org.chromium.base.ContextUtils;
 import org.chromium.base.PathUtils;
 import org.chromium.base.ThreadUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.ChromeActivity;
+import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.ChromeTabbedActivity2;
 import org.chromium.chrome.browser.IntentHandler;
 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.FeatureUtilities;
 import org.chromium.chrome.browser.util.UrlUtilities;
 import org.chromium.content_public.browser.LoadUrlParams;
 import org.chromium.content_public.common.Referrer;
 import org.chromium.ui.base.PageTransition;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.base.WindowAndroid.PermissionCallback;
 
 import java.util.List;
 
 /**
  * The main implementation of the {@link ExternalNavigationDelegate}.
  */
 public class ExternalNavigationDelegateImpl implements ExternalNavigationDelegate {
     private static final String TAG = "ExternalNavigationDelegateImpl";
     private static final String PDF_VIEWER = "com.google.android.apps.docs";
     private static final String PDF_MIME = "application/pdf";
     private static final String PDF_SUFFIX = ".pdf";
+    private static final String PDF_EXTENSION = "pdf";
 
     protected final Context mApplicationContext;
     private final Tab mTab;
 
     public ExternalNavigationDelegateImpl(Tab tab) {
         mTab = tab;
         mApplicationContext = tab.getWindowAndroid().getApplicationContext();
     }
 
     /**
@@ skipping 405 matching lines @@
             throw e;
         }
     }
 
     private void closeTab(Tab tab) {
         Context context = tab.getWindowAndroid().getContext().get();
         if (context instanceof ChromeActivity) {
             ((ChromeActivity) context).getTabModelSelector().closeTab(tab);
         }
     }
+
+    @Override
+    public boolean isPdfDownload(String url) {
+        if (ChromeFeatureList.isEnabled(ChromeFeatureList.SYSTEM_DOWNLOAD_MANAGER)) return false;
+
+        String fileExtension = MimeTypeMap.getFileExtensionFromUrl(url);
+        if (TextUtils.isEmpty(fileExtension)) return false;
+
+        return PDF_EXTENSION.equals(fileExtension);
+    }
 }