MD History: re-use history host constant from content/ instead of duplicating to chrome/

chrome/common/extensions/chrome_manifest_url_handlers.cc

Index: chrome/common/extensions/chrome_manifest_url_handlers.cc
diff --git a/chrome/common/extensions/chrome_manifest_url_handlers.cc b/chrome/common/extensions/chrome_manifest_url_handlers.cc
index cb6a0e9ec4858eded4e6eef20d342745f053640b..173b9558f70c8512c6adabc0025377bb97072afd 100644
--- a/chrome/common/extensions/chrome_manifest_url_handlers.cc
+++ b/chrome/common/extensions/chrome_manifest_url_handlers.cc
@@ -15,6 +15,7 @@
 #include "build/build_config.h"
 #include "chrome/common/chrome_constants.h"
 #include "chrome/common/url_constants.h"
+#include "content/public/common/url_constants.h"
 #include "extensions/common/error_utils.h"
 #include "extensions/common/file_util.h"
 #include "extensions/common/manifest.h"
@@ -108,7 +109,7 @@ bool URLOverridesHandler::Parse(Extension* extension, base::string16* error) {
     // Restrict override pages to a list of supported URLs.
     bool is_allowed_host = page == chrome::kChromeUINewTabHost ||
                            page == chrome::kChromeUIBookmarksHost ||
-                           page == chrome::kChromeUIHistoryHost;
+                           page == content::kChromeUIHistoryHost;
 #if defined(OS_CHROMEOS)
     is_allowed_host = is_allowed_host ||
                       page == chrome::kChromeUIActivationMessageHost ||