Move remaining files in content\browser to the content namespace.

content/browser/browsing_instance.cc

Index: content/browser/browsing_instance.cc
===================================================================
--- content/browser/browsing_instance.cc	(revision 164795)
+++ content/browser/browsing_instance.cc	(working copy)
@@ -12,9 +12,9 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/url_constants.h"
 
-using content::SiteInstance;
+namespace content {
 
-BrowsingInstance::BrowsingInstance(content::BrowserContext* browser_context)
+BrowsingInstance::BrowsingInstance(BrowserContext* browser_context)
     : browser_context_(browser_context) {
 }
 
@@ -83,3 +83,5 @@
   // us are gone.
   DCHECK(site_instance_map_.empty());
 }
+
+}  // namespace content