Add component for feature engagement tracking.

chrome/common/chrome_constants.cc

Index: chrome/common/chrome_constants.cc
diff --git a/chrome/common/chrome_constants.cc b/chrome/common/chrome_constants.cc
index 3734f21e3822944980f60e1d321fce183c9b7e45..04ed28ee4375bb4455c8f60155bb9f3794b78922 100644
--- a/chrome/common/chrome_constants.cc
+++ b/chrome/common/chrome_constants.cc
@@ -145,6 +145,8 @@ const base::FilePath::CharType kExtensionActivityLogFilename[] =
 const base::FilePath::CharType kExtensionsCookieFilename[] =
     FPL("Extension Cookies");
 const base::FilePath::CharType kFirstRunSentinel[] = FPL("First Run");
+const base::FilePath::CharType kFeatureEngagementTrackerStorageDirname[] =

[sky, 2017/03/31 00:10:15]

keep sorted (move above kFirstRunSentinel, which you have correctly in the .h).

[nyquist, 2017/03/31 00:15:40]

Oops! Thanks! Done.

+    FPL("Feature Engagement Tracker");
 const base::FilePath::CharType kGCMStoreDirname[] = FPL("GCM Store");
 const base::FilePath::CharType kLocalStateFilename[] = FPL("Local State");
 const base::FilePath::CharType kLocalStorePoolName[] = FPL("LocalStorePool");