Initial support for inspecting extension popups.

chrome/common/notification_type.h

Index: chrome/common/notification_type.h
diff --git a/chrome/common/notification_type.h b/chrome/common/notification_type.h
index 4b242daf14700940c91512729760fcbb19477b13..d1bb9664352ac8f8cd0a4736718b96dbbbaffbad 100644
--- a/chrome/common/notification_type.h
+++ b/chrome/common/notification_type.h
@@ -219,6 +219,10 @@ class NotificationType {
     // that was closed, no details are expected.
     WINDOW_CLOSED,
 
+    // Indicates that a devtools window is closing. The source is the Profile*
+    // and the details is the inspected RenderViewHost*.
+    DEVTOOLS_WINDOW_CLOSING,
+
     // Sent when an info bubble has been created but not yet shown. The source
     // is the InfoBubble.
     INFO_BUBBLE_CREATED,