Have HTMLMediaElement::play() return a Promise.

third_party/WebKit/Source/core/dom/DOMException.cpp

Index: third_party/WebKit/Source/core/dom/DOMException.cpp
diff --git a/third_party/WebKit/Source/core/dom/DOMException.cpp b/third_party/WebKit/Source/core/dom/DOMException.cpp
index a8b1414ebac5629ed43768d09c9953887f6c5821..719bbf87d98c9a00536b0aa0ea6db1500f54eebb 100644
--- a/third_party/WebKit/Source/core/dom/DOMException.cpp
+++ b/third_party/WebKit/Source/core/dom/DOMException.cpp
@@ -81,6 +81,12 @@ static const struct CoreException {
 
     // Push API
     { "PermissionDeniedError", "User or security policy denied the request.", 0 },
+
+    // Part of WebIDL. Used by HTML and Media Session API.

[philipj_slow, 2016/02/19 08:21:48]

I wanted to say "the above are also part of WebIDL", but apparently not. Filed:
https://github.com/w3c/push-api/issues/186

In any event most of the above are part of WebIDL. Putting things that aren't at
the end and adding a comment advising against adding any more without a WebIDL
issue might be good, but not your job if you don't want it.

[mlamouri (slow - plz ping), 2016/02/23 16:49:00]

Removed. "Part of WebIDL.". Though, I've added the ordering comment because I
tried to append this after "DataCloneError" and it was failing. It seems that
some code expect ordering so we shouldn't break this assumption.

+    { "NotAllowedError", "The request is not allowed by the user agent or the platform in the current context.", 0 },
+
+    // Please add new entries at the end of this list to guarantee any ordering

[philipj_slow, 2016/02/24 09:38:28]

There's a comment at the top ExceptionCode.h that says to keep the lists in
sync. Can you copy that to the top of this list as well? It's not really that
the order cannot change, it just has to change in multiple places. Unless
there's code comparing the ExceptionCode integer values?

[mlamouri (slow - plz ping), 2016/02/25 11:07:35]

Done. I will check what the error was exactly. It might be that someone was
comparing ExceptionCode.

[philipj_slow, 2016/02/25 14:06:48]

I also meant to imply that this comment at the bottom shouldn't be here, on the
assumption that it is actually OK to change the order. (I guess you're
investigating, just commenting so this warning isn't left without saying why
order cannot change.)

[mlamouri (slow - plz ping), 2016/02/25 14:40:05]

Removed. I'm going to investigate why that was needed but I don't want to block
this CL any more.

+    // expectations.
 };
 
 static const CoreException* getErrorEntry(ExceptionCode ec)