[Sync] Initial implementation of foreign sessions suggestions provider.

components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc

Index: components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
diff --git a/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc b/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
index 7e43abd335f02d5e5bbf5d688fa5b23443eb671c..3325447848009bb73553ed56cd1a045b288f9be6 100644
--- a/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
+++ b/components/ntp_snippets/bookmarks/bookmark_suggestions_provider.cc
@@ -29,6 +29,8 @@
 using bookmarks::BookmarkModel;
 using bookmarks::BookmarkNode;
 
+namespace ntp_snippets {
+
 namespace {
 
 const int kMaxBookmarks = 10;
@@ -43,53 +45,36 @@ const char* kUseCreationDateFallbackForDaysParamName =
     "bookmarks_creation_date_fallback_days";
 const char* kShowIfEmptyParamName = "bookmarks_show_if_empty";
 
+// Any bookmark created or visited after this time will be considered recent.
+// Note that bookmarks can be shown that do not meet this threshold.
 base::Time GetThresholdTime() {
-  std::string age_in_days_string = variations::GetVariationParamValueByFeature(
-    ntp_snippets::kBookmarkSuggestionsFeature, kMaxBookmarkAgeInDaysParamName);
-  int age_in_days = 0;
-  if (!base::StringToInt(age_in_days_string, &age_in_days)) {
-    if (!age_in_days_string.empty())
-      LOG(WARNING) << "Failed to parse bookmark age " << age_in_days_string;
-    age_in_days = kMaxBookmarkAgeInDays;
-  }
-  return base::Time::Now() - base::TimeDelta::FromDays(age_in_days);
+  return base::Time::Now() -
+         base::TimeDelta::FromDays(GetParamAsInt(
+             ntp_snippets::kBookmarkSuggestionsFeature,
+             kMaxBookmarkAgeInDaysParamName, kMaxBookmarkAgeInDays));
 }
 
+// The number of days used as a threshold where if this is larger than the time
+// since M54 started, then the creation timestamp of a bookmark be used as a
+// fallback if no last visited timestamp is present.
 int UseCreationDateFallbackForDays() {
-  std::string days_string = variations::GetVariationParamValueByFeature(
-      ntp_snippets::kBookmarkSuggestionsFeature,
-      kUseCreationDateFallbackForDaysParamName);
-  int days = 0;
-  if (!base::StringToInt(days_string, &days)) {
-    if (!days_string.empty())
-      LOG(WARNING) << "Failed to parse bookmark fallback days " << days_string;
-    days = kUseCreationDateFallbackForDays;
-  }
-  return days;
+  return GetParamAsInt(ntp_snippets::kBookmarkSuggestionsFeature,
+                       kUseCreationDateFallbackForDaysParamName,
+                       kUseCreationDateFallbackForDays);
 }
 
+// The maximum number of suggestions ever provided.
 int GetMaxCount() {
-  std::string max_count_string = variations::GetVariationParamValueByFeature(
-      ntp_snippets::kBookmarkSuggestionsFeature, kMaxBookmarksParamName);
-  int max_count = 0;
-  if (base::StringToInt(max_count_string, &max_count))
-    return max_count;
-  if (!max_count_string.empty())
-    LOG(WARNING) << "Failed to parse max bookmarks count " << max_count_string;
-
-  return kMaxBookmarks;
+  return GetParamAsInt(ntp_snippets::kBookmarkSuggestionsFeature,
+                       kMaxBookmarksParamName, kMaxBookmarks);
 }
 
+// The minimum number of suggestions to try to provide. Depending on other
+// parameters this may or not be respected. Currntly creation date fallback must

[battre, 2016/09/19 08:54:34]

nit: Currently

[skym, 2016/09/19 18:54:47]

Done.

+// be active in order for older bookmarks to be incorporated to meet this min.
 int GetMinCount() {
-  std::string min_count_string = variations::GetVariationParamValueByFeature(
-      ntp_snippets::kBookmarkSuggestionsFeature, kMinBookmarksParamName);
-  int min_count = 0;
-  if (base::StringToInt(min_count_string, &min_count))
-    return min_count;
-  if (!min_count_string.empty())
-    LOG(WARNING) << "Failed to parse min bookmarks count " << min_count_string;
-
-  return kMinBookmarks;
+  return GetParamAsInt(ntp_snippets::kBookmarkSuggestionsFeature,
+                       kMinBookmarksParamName, kMinBookmarks);
 }
 
 bool ShouldShowIfEmpty() {
@@ -106,8 +91,6 @@ bool ShouldShowIfEmpty() {
 
 }  // namespace
 
-namespace ntp_snippets {
-
 BookmarkSuggestionsProvider::BookmarkSuggestionsProvider(
     ContentSuggestionsProvider::Observer* observer,
     CategoryFactory* category_factory,