Set User-Agent and Accept-Language request headers for PWS requests

net/http/http_util.cc

 // Copyright (c) 2012 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.
 
 // The rules for parsing content-types were borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_util.h"
 
 #include <algorithm>
@@ skipping 737 matching lines @@
 }
 
 // TODO(jungshik): 1. If the list is 'fr-CA,fr-FR,en,de', we have to add
 // 'fr' after 'fr-CA' with the same q-value as 'fr-CA' because
 // web servers, in general, do not fall back to 'fr' and may end up picking
 // 'en' which has a lower preference than 'fr-CA' and 'fr-FR'.
 // 2. This function assumes that the input is a comma separated list
 // without any whitespace. As long as it comes from the preference and
 // a user does not manually edit the preference file, it's the case. Still,
 // we may have to make it more robust.
+// 3. The logic here is duplicated by generateAcceptLanguageHeader in
+// chrome/android/java/src/org/chromium/chrome/browser/
+//     physicalweb/PwsClientImpl.java
+// The two implementations should be kept in sync.

[asanka, 2016/05/27 16:57:59]

Let's remove this comment. I don't think its feasible to keep C++ and Java login
in sync via comments like these.

Is the PWS a purely Java implementation?

[mattreynolds, 2016/05/27 17:24:11]

The Physical Web client in Chrome for Android is by necessity implemented in
Java.  We don't want to load the native layer to resolve URLs or show
notifications when Chrome is in the background.

[asanka, 2016/06/01 20:10:26]

Understood. Thanks for removing the comment.

Would it be possible to determine the UA and Accept-Language headers while the
native portion is loaded and persist it somewhere for the Java code to access?
That way you won't need to worry about the languages preferences mismatches due
to duplicated code going out of sync. I imagine it would reduce the maintenance
burden and reduce the risk of subtle mysterious breakages down the line that
will probably remain unfixed.

[mattreynolds, 2016/06/01 22:02:48]

Yes, we could store it in SharedPreferences and update at a time when we know
native is loaded (eg, at Chrome startup).  However this would cause the header
to be out of sync whenever the user changes the system locale without restarting
Chrome.

 std::string HttpUtil::GenerateAcceptLanguageHeader(
     const std::string& raw_language_list) {
   // We use integers for qvalue and qvalue decrement that are 10 times
   // larger than actual values to avoid a problem with comparing
   // two floating point numbers.
   const unsigned int kQvalueDecrement10 = 2;
   unsigned int qvalue10 = 10;
   base::StringTokenizer t(raw_language_list, ",");
   std::string lang_list_with_q;
   while (t.GetNext()) {
@@ skipping 304 matching lines @@
   return true;
 }
 
 bool HttpUtil::NameValuePairsIterator::IsQuote(char c) const {
   if (strict_quotes_)
     return c == '"';
   return HttpUtil::IsQuote(c);
 }
 
 }  // namespace net