Initial work to remove the notion of all extension message payloads as strings.

chrome/browser/extensions/extension_event_router.cc

Index: chrome/browser/extensions/extension_event_router.cc
diff --git a/chrome/browser/extensions/extension_event_router.cc b/chrome/browser/extensions/extension_event_router.cc
index 9969514ad7b8901e927cb842874164cc8b0f00c9..e39cc55a1efc2df83f9f30fdbebc0f5cb9d5a01c 100644
--- a/chrome/browser/extensions/extension_event_router.cc
+++ b/chrome/browser/extensions/extension_event_router.cc
@@ -29,6 +29,7 @@
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/render_process_host.h"
 
+using base::Value;
 using content::BrowserThread;
 using extensions::Extension;
 using extensions::ExtensionAPI;
@@ -66,23 +67,50 @@ struct ExtensionEventRouter::ListenerProcess {
 
 struct ExtensionEventRouter::ExtensionEvent {
   std::string event_name;
-  std::string event_args;
+  scoped_ptr<Value> event_args;
   GURL event_url;
   Profile* restrict_to_profile;
-  std::string cross_incognito_args;
+  scoped_ptr<Value> cross_incognito_args;
   UserGestureState user_gesture;
 
   ExtensionEvent(const std::string& event_name,
+                 const Value& event_args,
+                 const GURL& event_url,
+                 Profile* restrict_to_profile,
+                 const Value& cross_incognito_args,
+                 UserGestureState user_gesture)
+    : event_name(event_name),
+      event_args(event_args.DeepCopy()),
+      event_url(event_url),
+      restrict_to_profile(restrict_to_profile),
+      cross_incognito_args(cross_incognito_args.DeepCopy()),
+      user_gesture(user_gesture) {}
+
+  ExtensionEvent(const std::string& event_name,
+                 const Value& event_args,
+                 const GURL& event_url,
+                 Profile* restrict_to_profile,
+                 UserGestureState user_gesture)
+    : event_name(event_name),
+      event_args(event_args.DeepCopy()),
+      event_url(event_url),
+      restrict_to_profile(restrict_to_profile),
+      cross_incognito_args(NULL),
+      user_gesture(user_gesture) {}
+
+  // TODO(gdk): This variant should be retired once the callers are switched to
+  // providing Values instead of just strings.
+  ExtensionEvent(const std::string& event_name,
                  const std::string& event_args,
                  const GURL& event_url,
                  Profile* restrict_to_profile,
                  const std::string& cross_incognito_args,
                  UserGestureState user_gesture)
     : event_name(event_name),
-      event_args(event_args),
+      event_args(Value::CreateStringValue(event_args)),
       event_url(event_url),
       restrict_to_profile(restrict_to_profile),
-      cross_incognito_args(cross_incognito_args),
+      cross_incognito_args(Value::CreateStringValue(cross_incognito_args)),
       user_gesture(user_gesture) {}
 };
 
@@ -90,17 +118,29 @@ struct ExtensionEventRouter::ExtensionEvent {
 void ExtensionEventRouter::DispatchEvent(IPC::Sender* ipc_sender,
                                          const std::string& extension_id,
                                          const std::string& event_name,
-                                         const std::string& event_args,
+                                         const Value& event_args,
                                          const GURL& event_url,
                                          UserGestureState user_gesture) {
   ListValue args;
   args.Set(0, Value::CreateStringValue(event_name));
-  args.Set(1, Value::CreateStringValue(event_args));
+  args.Set(1, event_args.DeepCopy());

[asargent_no_longer_on_chrome, 2012/06/18 16:25:30]

It's a bummer to have to copy the arguments just to hand off to be sent over the
IPC channel. Can you avoid the DeepCopy here by doing:

ListValue args;
args.Set(0, Value::CreateStringValue(event_name));
args.Set(1, static_cast<Value*>(&event_args));

...

// Take back ownership of event_args so it doesn't get deleted.
Value* tmp;
args.Remove(1, &tmp);

?

This can be a follow-up TODO though if you want. (I suppose for pedantry we
might consider changing event_args from const Value& to Value* to avoid needing
to cast away the constness).

[Garret Kelly, 2012/06/18 18:15:01]

I've added a TODO, I'll refactor that as part of the remaining changeover to
Value for event_args.

   ipc_sender->Send(new ExtensionMsg_MessageInvoke(MSG_ROUTING_CONTROL,
       extension_id, kDispatchEvent, args, event_url,
       user_gesture == USER_GESTURE_ENABLED));
 }
 
+// static
+void ExtensionEventRouter::DispatchEvent(IPC::Sender* ipc_sender,
+                                         const std::string& extension_id,
+                                         const std::string& event_name,
+                                         const std::string& event_args,
+                                         const GURL& event_url,
+                                         UserGestureState user_gesture) {
+  scoped_ptr<Value> event_args_value(Value::CreateStringValue(event_args));
+  DispatchEvent(ipc_sender, extension_id, event_name, *event_args_value.get(),
+                event_url, user_gesture);
+}
+
 ExtensionEventRouter::ExtensionEventRouter(Profile* profile)
     : profile_(profile),
       extension_devtools_manager_(
@@ -243,13 +283,13 @@ void ExtensionEventRouter::DispatchEventToRenderers(
 void ExtensionEventRouter::DispatchEventToExtension(
     const std::string& extension_id,
     const std::string& event_name,
-    const std::string& event_args,
+    const Value& event_args,
     Profile* restrict_to_profile,
     const GURL& event_url) {
   DCHECK(!extension_id.empty());
   linked_ptr<ExtensionEvent> event(
       new ExtensionEvent(event_name, event_args, event_url,
-                         restrict_to_profile, "", USER_GESTURE_UNKNOWN));
+                         restrict_to_profile, USER_GESTURE_UNKNOWN));
   DispatchEventImpl(extension_id, event);
 }
 
@@ -258,6 +298,17 @@ void ExtensionEventRouter::DispatchEventToExtension(
     const std::string& event_name,
     const std::string& event_args,
     Profile* restrict_to_profile,
+    const GURL& event_url) {
+  scoped_ptr<Value> event_args_value(Value::CreateStringValue(event_args));
+  DispatchEventToExtension(extension_id, event_name, *event_args_value.get(),
+                           restrict_to_profile, event_url);
+}
+
+void ExtensionEventRouter::DispatchEventToExtension(
+    const std::string& extension_id,
+    const std::string& event_name,
+    const std::string& event_args,
+    Profile* restrict_to_profile,
     const GURL& event_url,
     UserGestureState user_gesture) {
   DCHECK(!extension_id.empty());
@@ -326,7 +377,7 @@ void ExtensionEventRouter::DispatchEventToListener(
     return;
   }
 
-  const std::string* event_args;
+  const Value* event_args = NULL;
   if (!CanDispatchEventToProfile(listener_profile, extension,
                                  event, &event_args))
     return;
@@ -341,8 +392,8 @@ bool ExtensionEventRouter::CanDispatchEventToProfile(
     Profile* profile,
     const Extension* extension,
     const linked_ptr<ExtensionEvent>& event,
-    const std::string** event_args) {
-  *event_args = &event->event_args;
+    const Value** event_args) {
+  *event_args = event->event_args.get();
 
   // Is this event from a different profile than the renderer (ie, an
   // incognito tab event sent to a normal process, or vice versa).
@@ -350,11 +401,11 @@ bool ExtensionEventRouter::CanDispatchEventToProfile(
       profile != event->restrict_to_profile;
   if (cross_incognito &&
       !profile->GetExtensionService()->CanCrossIncognito(extension)) {
-    if (event->cross_incognito_args.empty())
+    if (!event->cross_incognito_args.get())
       return false;
     // Send the event with different arguments to extensions that can't
     // cross incognito.
-    *event_args = &event->cross_incognito_args;
+    *event_args = event->cross_incognito_args.get();
   }
 
   return true;
@@ -395,7 +446,7 @@ void ExtensionEventRouter::MaybeLoadLazyBackgroundPage(
     Profile* profile,
     const Extension* extension,
     const linked_ptr<ExtensionEvent>& event) {
-  const std::string* event_args;
+  const Value* event_args = NULL;
   if (!CanDispatchEventToProfile(profile, extension, event, &event_args))
     return;