Proof of concept implementation of context based history filtering.

components/history/core/browser/history_service.cc

Index: components/history/core/browser/history_service.cc
diff --git a/components/history/core/browser/history_service.cc b/components/history/core/browser/history_service.cc
index 75c5683270aaa751dbee08aafa3734c786eee0fa..fdcd059daab997d26520062c8314904db78423d6 100644
--- a/components/history/core/browser/history_service.cc
+++ b/components/history/core/browser/history_service.cc
@@ -428,6 +428,13 @@ void HistoryService::SetPageTitle(const GURL& url,
                                            history_backend_.get(), url, title));
 }
 
+void HistoryService::SetPageHistoryContext(const GURL& url,
+                                  HistoryContext context) {
+  DCHECK(thread_) << "History service being called after cleanup";
+  DCHECK(thread_checker_.CalledOnValidThread());
+  ScheduleTask(PRIORITY_NORMAL, base::Bind(&HistoryBackend::SetPageHistoryContext,
+                                           history_backend_.get(), url, context));
+}
 void HistoryService::UpdateWithPageEndTime(ContextID context_id,
                                            int nav_entry_id,
                                            const GURL& url,