Add support for GCM subtypes to desktop Instance ID implementation

chrome/browser/services/gcm/gcm_product_util.cc

+// Copyright 2016 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.
+
+#include "chrome/browser/services/gcm/gcm_product_util.h"
+
+#include "base/strings/string_piece.h"
+#include "base/strings/string_util.h"
+#include "chrome/common/channel_info.h"
+#include "chrome/common/chrome_version.h"
+#include "chrome/common/pref_names.h"
+#include "components/pref_registry/pref_registry_syncable.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+#include "components/version_info/version_info.h"
+
+namespace gcm {
+
+namespace {
+
+std::string ToLowerAlphaNum(base::StringPiece in) {
+  std::string out;
+  out.reserve(in.size());
+  for (char ch : in) {
+    if (base::IsAsciiAlpha(ch) || base::IsAsciiDigit(ch))
+      out.push_back(base::ToLowerASCII(ch));
+  }
+  return out;
+}
+
+}  // namespace
+
+std::string GetProductCategoryForSubtypes(PrefService* prefs) {
+  std::string product_category_for_subtypes =
+      prefs->GetString(prefs::kGCMProductCategoryForSubtypes);

[jianli, 2016/08/08 22:11:51]

Do we really need to save to prefs store? It seems that the generated category
value is fixed. Can we just construct it once and save to a static variable?

[johnme, 2016/08/10 13:09:55]

If the channel changes (e.g. because a user upgrades from stable to beta keeping
the same profile) or the PRODUCT_SHORTNAME_STRING changes (e.g. because a user
switches between chromium and chrome keeping the same profile), we must continue
to use the same string as the category sent to GCM for existing tokens.
Otherwise, things like deleteToken will fail because the category will not match
the one on the server.

+  if (!product_category_for_subtypes.empty())
+    return product_category_for_subtypes;
+
+  std::string product = ToLowerAlphaNum(PRODUCT_SHORTNAME_STRING);
+  std::string ns = product == "chromium" ? "org" : "com";
+  std::string channel =
+      ToLowerAlphaNum(version_info::GetChannelString(chrome::GetChannel()));
+  std::string platform = ToLowerAlphaNum(version_info::GetOSType());
+  product_category_for_subtypes =
+      ns + '.' + product + '.' + channel + '.' + platform;
+
+  prefs->SetString(prefs::kGCMProductCategoryForSubtypes,
+                   product_category_for_subtypes);
+  return product_category_for_subtypes;
+}
+
+void RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterStringPref(prefs::kGCMProductCategoryForSubtypes,
+                               std::string() /* default_value */);
+}
+
+void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry) {
+  RegisterPrefs(registry);
+}
+
+}  // namespace gcm