Add details to extension_manifest_fetcher's NetworkTrafficAnnotation

Bug: 812276
Change-Id: Ib5581eef0c5412c9ef9c157cf321efc964ace22f
Reviewed-on: https://chromium-review.googlesource.com/927343
Commit-Queue: proberge <proberge@chromium.org>
Reviewed-by: Karan Bhatia <karandeepb@chromium.org>
Reviewed-by: Thiemo Nagel <tnagel@chromium.org>
Reviewed-by: Joshua Pawlicki <waffles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539213}

extensions/browser/updater/extension_downloader.cc

@@ -507,8 +507,10 @@ void ExtensionDownloader::CreateManifestFetcher() {
             "An update timer indicates that it's time to update extensions, or "
             "a user triggers an extension update flow."
           data:
-            "The extension id, the user's chromium version, and a flag stating "
-            "if the request originated in the foreground or the background."
+            "The extension id, version and install source (the cause of the "
+            "update flow). The client's OS, architecture, language, Chromium "
+            "version, channel and a flag stating whether the request originated"
+            "in the foreground or the background."
           destination: WEBSITE
         }
         policy {

tools/traffic_annotation/summary/annotations.xml

@@ -89,7 +89,7 @@ Refer to README.md for content description and update process.
  <item id="extension_blacklist" hash_code="59592717" type="0" content_hash_code="116742516" os_list="linux,windows" file_path="chrome/browser/extensions/blacklist_state_fetcher.cc"/>
  <item id="extension_crx_fetcher" hash_code="21145003" type="0" content_hash_code="79150319" os_list="linux,windows" file_path="extensions/browser/updater/extension_downloader.cc"/>
  <item id="extension_install_signer" hash_code="50464499" type="0" content_hash_code="88088656" os_list="linux,windows" file_path="chrome/browser/extensions/install_signer.cc"/>
- <item id="extension_manifest_fetcher" hash_code="5151071" type="0" content_hash_code="57885402" os_list="linux,windows" file_path="extensions/browser/updater/extension_downloader.cc"/>
+ <item id="extension_manifest_fetcher" hash_code="5151071" type="0" content_hash_code="25187227" os_list="linux,windows" file_path="extensions/browser/updater/extension_downloader.cc"/>
  <item id="external_policy_fetcher" hash_code="9459438" type="0" content_hash_code="64260484" os_list="linux,windows" file_path="components/policy/core/common/cloud/external_policy_data_fetcher.cc"/>
  <item id="family_info" hash_code="30913825" type="0" content_hash_code="25369370" os_list="linux,windows" file_path="chrome/browser/supervised_user/child_accounts/family_info_fetcher.cc"/>
  <item id="favicon_loader" hash_code="112189210" type="0" content_hash_code="70773116" os_list="linux,windows" file_path="content/renderer/loader/web_url_loader_impl.cc"/>