Run content scripts in their own isolated world.

webkit/glue/webframe_impl.cc

Index: webkit/glue/webframe_impl.cc
===================================================================
--- webkit/glue/webframe_impl.cc	(revision 18892)
+++ webkit/glue/webframe_impl.cc	(working copy)
@@ -131,7 +131,9 @@
 
 #undef LOG
 
+#include "base/base_switches.h"
 #include "base/basictypes.h"
+#include "base/command_line.h"
 #include "base/gfx/rect.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
@@ -1695,7 +1697,10 @@
         sources_in[i].startLine));
   }
 
-  frame_->script()->evaluateInNewContext(sources);
+  if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kIsolatedWorld))
+    frame_->script()->evaluateInNewWorld(sources);
+  else
+    frame_->script()->evaluateInNewContext(sources);
 }
 
 std::wstring WebFrameImpl::GetName() {