[Extensions] Use document url (not top url) for tab-specific permissions

extensions/common/extension_messages.h

Index: extensions/common/extension_messages.h
diff --git a/extensions/common/extension_messages.h b/extensions/common/extension_messages.h
index 56855be4175a8c9619df5b581e29a3018e8ab952..bdae495ec88843d2b2c2fc816c0585a2be4d5ca5 100644
--- a/extensions/common/extension_messages.h
+++ b/extensions/common/extension_messages.h
@@ -424,6 +424,11 @@ IPC_MESSAGE_CONTROL2(ExtensionMsg_SetSystemFont,
 IPC_MESSAGE_CONTROL1(ExtensionMsg_ActivateExtension,
                      std::string /* extension_id */)
 
+// Notifies the renderer that the current tab is an extension page (we limit
+// what other extensions can do on these pages).
+IPC_MESSAGE_ROUTED1(ExtensionMsg_SetTabExtensionOwner,

[not at google - send to devlin, 2015/06/03 20:15:45]

Btw I think maybe we should own up and call this "SetTopFrameURL" or similar -
"Owner" seems ambiguous to me.

[Devlin, 2015/06/03 20:28:47]

Waiting to hear back from Nasko or Charlie before renaming.  For the record, I
chose the current name because I wanted it more clear that we're not sending
across the top frame url - we're sending across whether or not this tab is an
extension page, and, if so, which extension owns it.  There's a subtle
difference, but I think it's important from an architectural standpoint.

+                    std::string /* extension_id */);
+
 // Notifies the renderer that extensions were loaded in the browser.
 IPC_MESSAGE_CONTROL1(ExtensionMsg_Loaded,
                      std::vector<ExtensionMsg_Loaded_Params>)