Move ntp_tiles classes to namespace ntp_tiles.

components/ntp_tiles/popular_sites.h

Index: components/ntp_tiles/popular_sites.h
diff --git a/components/ntp_tiles/popular_sites.h b/components/ntp_tiles/popular_sites.h
index 856526ccc98951cd8256933d63f0ef97a8f6055b..cfb23dfe6c221ac82dfc544ff3a2edd72a61c531 100644
--- a/components/ntp_tiles/popular_sites.h
+++ b/components/ntp_tiles/popular_sites.h
@@ -36,6 +36,8 @@ class VariationsService;
 class PrefService;
 class TemplateURLService;
 
+namespace ntp_tiles {
+
 // Downloads and provides a list of suggested popular sites, for display on
 // the NTP when there are not enough personalized suggestions. Caches the
 // downloaded file on disk to avoid re-downloading on every startup.
@@ -150,4 +152,6 @@ class PopularSites : public net::URLFetcherDelegate {
   DISALLOW_COPY_AND_ASSIGN(PopularSites);
 };
 
+}  // namespace ntp_tiles
+
 #endif  // COMPONENTS_NTP_TILES_POPULAR_SITES_H_