Hide requests in an extension from other extensions

extensions/browser/api/web_request/web_request_api.cc

Index: extensions/browser/api/web_request/web_request_api.cc
diff --git a/extensions/browser/api/web_request/web_request_api.cc b/extensions/browser/api/web_request/web_request_api.cc
index 801e58dfe539abb0035c42ec723b76cb05d80043..04a2beda3e0169586936ec5008e89d5e13b0b2a7 100644
--- a/extensions/browser/api/web_request/web_request_api.cc
+++ b/extensions/browser/api/web_request/web_request_api.cc
@@ -416,7 +416,7 @@ void WebRequestAPI::OnListenerRemoved(const EventListenerInfo& details) {
                                      details.browser_context,
                                      details.extension_id,
                                      details.event_name,
-                                     0 /* embedder_process_id */,
+                                     0 /* embedder_process_id (ignored) */,
                                      0 /* web_view_instance_id */));
 }
 
@@ -445,12 +445,21 @@ struct ExtensionWebRequestEventRouter::EventListener {
     if (sub_event_name != that.sub_event_name)
       return sub_event_name < that.sub_event_name;
 
-    if (embedder_process_id != that.embedder_process_id)
-      return embedder_process_id < that.embedder_process_id;
-
     if (web_view_instance_id != that.web_view_instance_id)
       return web_view_instance_id < that.web_view_instance_id;
 
+    if (web_view_instance_id == 0) {
+      // Do not filter by process ID for non-webviews, because this comparator
+      // is also used to find and remove an event listener when an extension is
+      // unloaded. At this point, the event listener cannot be mapped back to
+      // the original process, so 0 is used instead of the actual process ID.
+      DCHECK(embedder_process_id == 0 || that.embedder_process_id == 0);
+      return false;
+    }
+
+    if (embedder_process_id != that.embedder_process_id)
+      return embedder_process_id < that.embedder_process_id;
+
     return false;
   }
 
@@ -1238,6 +1247,8 @@ void ExtensionWebRequestEventRouter::OnEventHandled(
     const std::string& sub_event_name,
     uint64 request_id,
     EventResponse* response) {
+  // TODO(robwu): Does this also work with webviews? operator< (used by find)
+  // takes the webview ID into account, which is not set on |listener|.
   EventListener listener;
   listener.extension_id = extension_id;
   listener.sub_event_name = sub_event_name;
@@ -1470,6 +1481,12 @@ void ExtensionWebRequestEventRouter::GetMatchingListenersImpl(
          it->web_view_instance_id != web_view_info.instance_id))
       continue;
 
+    // Filter requests from other extensions / apps. This does not work for
+    // content scripts, or extension pages in non-extension processes.

[battre, 2015/08/05 13:49:46]

Also extensions can be hosted in the same process. Would these be filtered?

[robwu, 2015/08/05 16:38:09]

You mean another extension within some webRequest extension?
With site isolation: Yes.
Without site isolation: No, but the frame cannot be embedded anyway unless the
page is in web_accessible_resources.

[not at google - send to devlin, 2015/08/05 16:49:59]

I think the question is can extensions share a render process host ID?

I had always assumed that an RPH is an abstraction of a process, so the process
manager infrastructure can choose to host two RPHs in the same OS process but
that's an implementation detail.

However come to think of it I've never actually asked anybody that question.

+    if (is_request_from_extension &&
+        it->embedder_process_id != render_process_host_id)
+      continue;
+
     if (!it->filter.urls.is_empty() && !it->filter.urls.MatchesURL(url))
       continue;
     if (web_request_event_router_delegate_ &&
@@ -2190,9 +2207,7 @@ bool WebRequestInternalAddEventListenerFunction::RunSync() {
   EXTENSION_FUNCTION_VALIDATE(args_->GetInteger(5, &web_view_instance_id));
 
   base::WeakPtr<IOThreadExtensionMessageFilter> ipc_sender = ipc_sender_weak();
-  int embedder_process_id =
-      ipc_sender.get() && web_view_instance_id > 0 ?
-          ipc_sender->render_process_id() : 0;
+  int embedder_process_id = ipc_sender ? ipc_sender->render_process_id() : 0;
 
   const Extension* extension =
       extension_info_map()->extensions().GetByID(extension_id_safe());