Relanding this as the previous attempt failed due to build errors.

webkit/plugins/npapi/plugin_utils.cc

Index: webkit/plugins/npapi/plugin_utils.cc
===================================================================
--- webkit/plugins/npapi/plugin_utils.cc	(revision 200310)
+++ webkit/plugins/npapi/plugin_utils.cc	(working copy)
@@ -13,6 +13,9 @@
 namespace webkit {
 namespace npapi {
 
+// Global variable used by the plugin quirk "die after unload".
+bool g_forcefully_terminate_plugin_process = false;
+
 void CreateVersionFromString(const base::string16& version_string,
                              Version* parsed_version) {
   // Remove spaces and ')' from the version string,
@@ -52,5 +55,13 @@
 #endif
 }
 
+void SetForcefullyTerminatePluginProcess(bool value) {
+  g_forcefully_terminate_plugin_process = value;
+}
+
+bool ShouldForcefullyTerminatePluginProcess() {
+  return g_forcefully_terminate_plugin_process;
+}
+
 }  // namespace npapi
 }  // namespace webkit