Add ClearHistory() to ContentSuggestionsService and its providers

components/ntp_snippets/content_suggestions_provider.h

Index: components/ntp_snippets/content_suggestions_provider.h
diff --git a/components/ntp_snippets/content_suggestions_provider.h b/components/ntp_snippets/content_suggestions_provider.h
index c7fcd056abacc51b0d30dabb2bef7d3d5ace1d67..8d292523a75b6d6c07a27b9f549105d9798ca172 100644
--- a/components/ntp_snippets/content_suggestions_provider.h
+++ b/components/ntp_snippets/content_suggestions_provider.h
@@ -102,6 +102,14 @@ class ContentSuggestionsProvider {
   virtual void FetchSuggestionImage(const std::string& suggestion_id,
                                     const ImageFetchedCallback& callback) = 0;
 
+  // Removes history from a given time range. The data removed depends on a

[Marc Treib, 2016/08/30 09:50:18]

depends on *the* provider

[vitaliii, 2016/08/30 11:04:21]

Done.

+  // provider. Note that the data outside the time range may be deleted, for
+  // example suggestions, which are based on the time range. Providers should

[Marc Treib, 2016/08/30 09:50:18]

"which are based on the time range" isn't very clear IMO... "which are based on
history from that time range" maybe?

[vitaliii, 2016/08/30 11:04:22]

Done.

+  // immediately clear any specified time range history-related data, such as

[Marc Treib, 2016/08/30 09:50:18]

This doesn't grammar - "clear any history-related data from the specified time
range" ?

[vitaliii, 2016/08/30 11:04:22]

Done.

+  // (possibly dismissed) suggestions for NTPSnippetsService or in case of
+  // BookmarkSuggestionsProvider last visit dates.
+  virtual void ClearHistory(base::Time begin, base::Time end) = 0;
+
   // Clears all caches for the given category, so that the next fetch starts
   // from scratch.
   virtual void ClearCachedSuggestions(Category category) = 0;