Pass user session type to extension feature checks

extensions/browser/renderer_startup_helper.cc

Index: extensions/browser/renderer_startup_helper.cc
diff --git a/extensions/browser/renderer_startup_helper.cc b/extensions/browser/renderer_startup_helper.cc
index 452c816963ddd1b509e6b12ea30c540b9b7ce566..4311172206652cd58de81ad9df06703c09eafc1c 100644
--- a/extensions/browser/renderer_startup_helper.cc
+++ b/extensions/browser/renderer_startup_helper.cc
@@ -17,6 +17,7 @@
 #include "extensions/common/extension_set.h"
 #include "extensions/common/extensions_client.h"
 #include "extensions/common/features/feature_channel.h"
+#include "extensions/common/features/feature_session_type.h"
 #include "ui/base/webui/web_ui_util.h"
 
 using content::BrowserContext;
@@ -70,6 +71,14 @@ void RendererStartupHelper::InitializeProcess(
   // to all renderers, as the non-extension renderers may have content scripts.
   process->Send(new ExtensionMsg_SetChannel(GetCurrentChannel()));
 
+  // Extensions need to know the session type for API restrictions. The session
+  // type is determined based on the user for which the current session is

[Devlin, 2016/08/18 17:19:15]

omit "The session type is determined..." - that's something that should be said
(or immediately apparent) from GetCurrentFeatureSessionType().

+  // started.
+  // The value is sent to all renderers, as the non-extension renderers may have
+  // content scripts.
+  process->Send(

[Devlin, 2016/08/18 17:19:15]

IPCs aren't free, and I think it's probably cheaper to just put this along with
Channel, since they are used for very similar reasons and both always sent.

+      new ExtensionMsg_SetUserSessionType(GetCurrentFeatureSessionType()));
+
   // Platform apps need to know the system font.
   // TODO(dbeam): this is not the system font in all cases.
   process->Send(new ExtensionMsg_SetSystemFont(webui::GetFontFamily(),