Proof of concept implementation of context based history filtering.

components/history/core/browser/url_row.cc

Index: components/history/core/browser/url_row.cc
diff --git a/components/history/core/browser/url_row.cc b/components/history/core/browser/url_row.cc
index 1f484c88c2bc8422ec40943bbe3faf17e75653d2..75935b5917656e609074dbadea01602420027653 100644
--- a/components/history/core/browser/url_row.cc
+++ b/components/history/core/browser/url_row.cc
@@ -35,6 +35,7 @@ URLRow& URLRow::operator=(const URLRow& other) {
   typed_count_ = other.typed_count_;
   last_visit_ = other.last_visit_;
   hidden_ = other.hidden_;
+  context_ = other.context_;
   return *this;
 }
 
@@ -46,6 +47,7 @@ void URLRow::Swap(URLRow* other) {
   std::swap(typed_count_, other->typed_count_);
   std::swap(last_visit_, other->last_visit_);
   std::swap(hidden_, other->hidden_);
+  std::swap(context_, other->context_);
 }
 
 void URLRow::Initialize() {
@@ -54,6 +56,7 @@ void URLRow::Initialize() {
   typed_count_ = 0;
   last_visit_ = base::Time();
   hidden_ = false;
+  context_ = CONTEXT_NONE;
 }