Move constants used by history component to history namespace.
Add history_constants.cc/h for history specific constants.
BUG=390953
TEST=unit_tests
Review URL: https://codereview.chromium.org/722723005
Cr-Commit-Position: refs/heads/master@{#306130}
diff --git a/components/history.gypi b/components/history.gypi
index 870d866d..2fd1cbd 100644
--- a/components/history.gypi
+++ b/components/history.gypi
@@ -28,6 +28,8 @@
'history/core/browser/history_backend_observer.h',
'history/core/browser/history_client.cc',
'history/core/browser/history_client.h',
+ 'history/core/browser/history_constants.cc',
+ 'history/core/browser/history_constants.h',
'history/core/browser/history_match.cc',
'history/core/browser/history_match.h',
'history/core/browser/history_service_observer.h',
