Move ntp_tiles classes to namespace ntp_tiles.

components/ntp_tiles/popular_sites.cc

Index: components/ntp_tiles/popular_sites.cc
diff --git a/components/ntp_tiles/popular_sites.cc b/components/ntp_tiles/popular_sites.cc
index 2012fdbcbee91753ebba716521394cf9b048ac00..b5df0976f85ed74d6a17038d5a3be4a7c49ce542 100644
--- a/components/ntp_tiles/popular_sites.cc
+++ b/components/ntp_tiles/popular_sites.cc
@@ -35,6 +35,8 @@
 using net::URLFetcher;
 using variations::VariationsService;
 
+namespace ntp_tiles {
+
 namespace {
 
 const char kPopularSitesURLFormat[] =
@@ -400,3 +402,5 @@ void PopularSites::OnDownloadFailed() {
     callback_.Run(false);
   }
 }
+
+}  // namespace ntp_tiles