[Sync] Initial implementation of foreign sessions suggestions provider.

components/ntp_snippets/features.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 "components/ntp_snippets/features.h"
 
+#include "base/strings/string_number_conversions.h"
+#include "components/variations/variations_associated_data.h"
+
 namespace ntp_snippets {
 
 const base::Feature kArticleSuggestionsFeature{
     "NTPArticleSuggestions", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kBookmarkSuggestionsFeature{
     "NTPBookmarkSuggestions", base::FEATURE_ENABLED_BY_DEFAULT};
 
 const base::Feature kRecentOfflineTabSuggestionsFeature{
     "NTPOfflinePageSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kSaveToOfflineFeature{
     "NTPSaveToOffline", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kDownloadSuggestionsFeature{
     "NTPDownloadSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kPhysicalWebPageSuggestionsFeature{
     "NTPPhysicalWebPageSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kContentSuggestionsFeature{
     "NTPSnippets", base::FEATURE_ENABLED_BY_DEFAULT};
 
+const base::Feature kForeignSessionsSuggestionsFeature{
+    "NTPForeignSessionsSuggestions", base::FEATURE_DISABLED_BY_DEFAULT};
+
+int GetParamAsInt(const base::Feature& feature,
+                  const std::string& param_name,
+                  const int default_value) {
+  std::string value_as_string =
+      variations::GetVariationParamValueByFeature(feature, param_name);
+  int value_as_int;

[Marc Treib, 2016/09/16 12:26:48]

I think some compilers will complain if you don't initialize this.

[skym, 2016/09/16 18:18:48]

Done.

+  if (!base::StringToInt(value_as_string, &value_as_int)) {
+    if (!value_as_string.empty()) {
+      LOG(WARNING) << "Failed to parse variation param " << param_name
+                   << " with string value " << value_as_string
+                   << " under feature " << feature.name
+                   << " into an int. Falling back to default value of "
+                   << default_value;
+    }
+    value_as_int = default_value;
+  }
+  return value_as_int;
+}
+
 }  // namespace ntp_snippets