Move content's a plugin, ppapi_plugin, utility, and worker subdirectories to the content namespace.

content/plugin/plugin_main.cc

Index: content/plugin/plugin_main.cc
===================================================================
--- content/plugin/plugin_main.cc	(revision 163080)
+++ content/plugin/plugin_main.cc	(working copy)
@@ -29,6 +29,8 @@
 #include "ipc/ipc_descriptors.h"
 #endif
 
+namespace content {
+
 #if defined(OS_MACOSX)
 // Removes our Carbon library interposing from the environment so that it
 // doesn't carry into any processes that plugins might start.
@@ -42,7 +44,7 @@
 #endif
 
 // main() routine for running as the plugin process.
-int PluginMain(const content::MainFunctionParams& parameters) {
+int PluginMain(const MainFunctionParams& parameters) {
   // The main thread of the plugin services UI.
 #if defined(OS_MACOSX)
 #if !defined(__LP64__)
@@ -80,3 +82,5 @@
 
   return 0;
 }
+
+}  // namespace content