Jian, could you take a look at it? Thanks!

Also, the button in 3-dot menu should not get disabled when download is initiated. This is purposefully different from the big blue button on the dino page itself, which does get disabled when it happens.

Should we enable Download button when the error page only contains "Reload" button for certain types of errors? I assume we want to be consistent with when to show "DOWNLOAD PAGE LATER" in error page.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b0fe12b996f99d984f92983d188b7095b8c80134

commit b0fe12b996f99d984f92983d188b7095b8c80134
Author: jianli <jianli@chromium.org>
Date: Thu Jan 12 01:14:08 2017

Enable download page action for error page

If error page shows "DOWNLOAD PAGE LATER" button, we should also
enable download page action.

BUG= 675225 

Patch

Review-Url: https://codereview.chromium.org/2588253002
Cr-Commit-Position: refs/heads/master@{#443104}

[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/android/java/src/org/chromium/chrome/browser/download/DownloadUtils.java
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/android/java/src/org/chromium/chrome/browser/offlinepages/OfflinePageBridge.java
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/android/offline_pages/offline_page_bridge.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/android/offline_pages/offline_page_bridge.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/android/offline_pages/offline_page_utils.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/android/offline_pages/offline_page_utils.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/net/net_error_tab_helper.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/net/net_error_tab_helper.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/browser/net/net_error_tab_helper_unittest.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/common/render_messages.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/renderer/net/net_error_helper.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/chrome/renderer/net/net_error_helper.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/components/error_page/renderer/net_error_helper_core.cc
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/components/error_page/renderer/net_error_helper_core.h
[modify] https://crrev.com/b0fe12b996f99d984f92983d188b7095b8c80134/components/error_page/renderer/net_error_helper_core_unittest.cc