Get rid of content dependency from sandbox_policy.h

chrome/browser/chrome_content_browser_client.h

Index: chrome/browser/chrome_content_browser_client.h
===================================================================
--- chrome/browser/chrome_content_browser_client.h	(revision 86986)
+++ chrome/browser/chrome_content_browser_client.h	(working copy)
@@ -44,6 +44,11 @@
   // Can return an optional fd for crash handling, otherwise returns -1.
   virtual int GetCrashSignalFD(const std::string& process_type);
 #endif
+
+#if defined(OS_WIN)
+  virtual bool SandboxPlugin(CommandLine* command_line,
+                             sandbox::TargetPolicy* policy);
+#endif
 };
 
 }  // namespace chrome