OOPIF: Handle cross-site frames being blocked by X-Frame-Options or CSP.

content/common/frame_messages.h

Index: content/common/frame_messages.h
diff --git a/content/common/frame_messages.h b/content/common/frame_messages.h
index b990cdb6c8ad08169870c8ce5dded0f811622d52..94864c571608401e38a96ce7d2600206755f6ccc 100644
--- a/content/common/frame_messages.h
+++ b/content/common/frame_messages.h
@@ -846,6 +846,10 @@ IPC_MESSAGE_ROUTED1(FrameMsg_SerializeAsMHTML, FrameMsg_SerializeAsMHTML_Params)
 IPC_MESSAGE_ROUTED1(FrameMsg_SetFrameOwnerProperties,
                     blink::WebFrameOwnerProperties /* frame_owner_properties */)
 
+// Notifies the frame that its load was blocked by X-Frame-Options or CSP
+// frame-ancestors while loading.
+IPC_MESSAGE_ROUTED0(FrameMsg_CancelLoadAfterXFrameOptionsOrCSPDenied)

[Charlie Reis, 2016/02/26 01:13:22]

Is there a reason to make this specific to these features?  I'm wondering if
there's a more general "blocked load" concept that this might cover.

[alexmos, 2016/02/26 02:38:05]

Good question.  It's only specific in the sense that we do some special stuff in
the parent frame (that the spec requires) so that it can't determine whether the
child was blocked or not (i.e., dispatch the load event on the iframe element,
change the blocked frame's origin to unique).  I don't know of anything else
besides XFO+CSP that needs this at the moment, but there might be other kinds of
blocked loads in the future that might reuse this (e.g., clickjacking
protection), so maybe this whole plumbing should be renamed to 
FrameMsg_BlockedLoad, etc.  WDYT?  I really like that this would simplify all
the names. :)

[Charlie Reis, 2016/02/26 21:10:01]

Yeah, let's make it BlockedLoad, with documentation about all the things it does
(and the motivation).  That should make it a bit easier to follow, and possibly
easier to reuse later.

+
 // Request to continue running the sequential focus navigation algorithm in
 // this frame.  |source_routing_id| identifies the frame that issued this
 // request.  This message is sent when pressing <tab> or <shift-tab> needs to
@@ -995,6 +999,13 @@ IPC_MESSAGE_ROUTED2(FrameHostMsg_DidChangeFrameOwnerProperties,
                     int32_t /* subframe_routing_id */,
                     blink::WebFrameOwnerProperties /* frame_owner_properties */)
 
+// Notifies the browser process that a subframe was blocked by
+// X-Frame-Options or CSP frame-ancestors while loading.
+//
+// TODO(mkwst, alexmos): This will become unnecessary once X-Frame-Options and
+// CSP enforcement moves to the browser process (https://crbug.com/555418).
+IPC_MESSAGE_ROUTED0(FrameHostMsg_DidCancelLoadAfterXFrameOptionsOrCSPDenied)
+
 // Changes the title for the page in the UI when the page is navigated or the
 // title changes. Sent for top-level frames.
 IPC_MESSAGE_ROUTED2(FrameHostMsg_UpdateTitle,