content: Use stl utilities from the base namespace

The utilities in base/stl_util.h have been moved from the global
into the base namespace. This patch updates the call sites accordingly.

No functional changes.

BUG=636301
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2228403003
Cr-Commit-Position: refs/heads/master@{#411614}
diff --git a/content/browser/host_zoom_map_impl.cc b/content/browser/host_zoom_map_impl.cc
index edf1f78c..4eab76d5 100644
--- a/content/browser/host_zoom_map_impl.cc
+++ b/content/browser/host_zoom_map_impl.cc
@@ -440,14 +440,14 @@
   RenderViewKey key(render_process_id, render_view_id);
 
   base::AutoLock auto_lock(lock_);
-  return ContainsKey(temporary_zoom_levels_, key);
+  return base::ContainsKey(temporary_zoom_levels_, key);
 }
 
 double HostZoomMapImpl::GetTemporaryZoomLevel(int render_process_id,
                                               int render_view_id) const {
   base::AutoLock auto_lock(lock_);
   RenderViewKey key(render_process_id, render_view_id);
-  if (!ContainsKey(temporary_zoom_levels_, key))
+  if (!base::ContainsKey(temporary_zoom_levels_, key))
     return 0;
 
   return temporary_zoom_levels_.find(key)->second;
@@ -483,7 +483,7 @@
   RenderViewKey key(render_process_id, render_view_id);
   base::AutoLock auto_lock(lock_);
 
-  if (ContainsKey(temporary_zoom_levels_, key))
+  if (base::ContainsKey(temporary_zoom_levels_, key))
     return temporary_zoom_levels_.find(key)->second;
 
   return GetZoomLevelForHostAndSchemeInternal(url.scheme(),