Move the event attach/detach logic on unload from event.js to

extensions/renderer/module_system.cc

Index: extensions/renderer/module_system.cc
diff --git a/extensions/renderer/module_system.cc b/extensions/renderer/module_system.cc
index 6194b8ed4c4be059a5f298055d91df3b00bc4cab..6a120749f4107499b322fc42f998c9f83528a703 100644
--- a/extensions/renderer/module_system.cc
+++ b/extensions/renderer/module_system.cc
@@ -6,6 +6,7 @@
 
 #include "base/bind.h"
 #include "base/command_line.h"
+#include "base/logging.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
@@ -151,12 +152,10 @@ ModuleSystem::ModuleSystem(ScriptContext* context, SourceMap* source_map)
   }
 }
 
-ModuleSystem::~ModuleSystem() { Invalidate(); }
+ModuleSystem::~ModuleSystem() {
+}
 
 void ModuleSystem::Invalidate() {
-  if (!is_valid())
-    return;
-
   // Clear the module system properties from the global context. It's polite,
   // and we use this as a signal in lazy handlers that we no longer exist.
   {
@@ -168,12 +167,11 @@ void ModuleSystem::Invalidate() {
         v8::String::NewFromUtf8(GetIsolate(), kModuleSystem));
   }
 
-  // Invalidate all of the successfully required handlers we own.
-  for (NativeHandlerMap::iterator it = native_handler_map_.begin();
-       it != native_handler_map_.end();
-       ++it) {
-    it->second->Invalidate();
-  }
+  // Invalidate all active and clobbered NativeHandlers we own.
+  for (const auto& handler : native_handler_map_)
+    handler.second->Invalidate();
+  for (const auto& clobbered_handler : clobbered_native_handlers_)
+    clobbered_handler->Invalidate();
 
   ObjectBackedNativeHandler::Invalidate();
 }
@@ -301,11 +299,13 @@ v8::Local<v8::Value> ModuleSystem::CallModuleMethod(
 void ModuleSystem::RegisterNativeHandler(
     const std::string& name,
     scoped_ptr<NativeHandler> native_handler) {
+  ClobberExistingNativeHandler(name);
   native_handler_map_[name] =
       linked_ptr<NativeHandler>(native_handler.release());
 }
 
 void ModuleSystem::OverrideNativeHandlerForTest(const std::string& name) {
+  ClobberExistingNativeHandler(name);
   overridden_native_handlers_.insert(name);
 }
 
@@ -685,4 +685,12 @@ void ModuleSystem::OnModuleLoaded(
   resolver_local->Resolve(value);
 }
 
+void ModuleSystem::ClobberExistingNativeHandler(const std::string& name) {
+  NativeHandlerMap::iterator existing_handler = native_handler_map_.find(name);
+  if (existing_handler != native_handler_map_.end()) {
+    clobbered_native_handlers_.push_back(existing_handler->second);
+    native_handler_map_.erase(existing_handler);
+  }
+}
+
 }  // namespace extensions