Implement Custom Elements

Implement Custom Elements

This CL implements custom elements. The design is as follows:

1) Authors subclass Element and call registerElement.
2) When we create C++ elements for custom elements, we call the author's
   constructor synchronously.
3) The attach/detach/attributeChanged callbacks are called either:
   a) when exiting the current custom element callback scoped (e.g., before
      returning from appendChild), or
   b) when draining the microtask queue.

The implementation in this CL is a bit fragile because we don't detect name
registration conflicts and we let you create custom elements with the same name
as built-in elements. Also, not every part of the engine is prepared to execute
script synchronously below createElement. We'll need to iron out these issues
over time, but this CL is a start.

R=ojan@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/2d2d1918a543b85e2c13134af4aee6d790f4c864

[ojan, 2015-02-20 23:09:33]

ojan@chromium.org changed reviewers:
+ ojan@chromium.org

[ojan, 2015-02-20 23:09:34]

lgtm. Elliott should probably review too, but that doesn't necessarily need to
block landing.

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/Elem...
File sky/engine/core/dom/Element.cpp (right):

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/Elem...
sky/engine/core/dom/Element.cpp:95:
element->setCustomElementState(Element::Upgraded);
Presumablye we should add a TODO to get rid of these states?

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/cust...
File sky/engine/core/dom/custom2/new_custom_element.cc (right):

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/cust...
sky/engine/core/dom/custom2/new_custom_element.cc:34: auto* dart_state =
element->document().elementRegistry().dart_state().get();
bikeshed: I don't know that it makes sense to use chrome style within
directories that are already blink style. My vote would be to move directories
at a time. But...I don't feel too strongly.

[abarth-chromium, 2015-02-21 00:00:45]

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/Elem...
File sky/engine/core/dom/Element.cpp (right):

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/Elem...
sky/engine/core/dom/Element.cpp:95:
element->setCustomElementState(Element::Upgraded);
On 2015/02/20 at 23:09:34, ojan wrote:
> Presumablye we should add a TODO to get rid of these states?

Done.

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/cust...
File sky/engine/core/dom/custom2/new_custom_element.cc (right):

https://codereview.chromium.org/943013002/diff/20001/sky/engine/core/dom/cust...
sky/engine/core/dom/custom2/new_custom_element.cc:34: auto* dart_state =
element->document().elementRegistry().dart_state().get();
On 2015/02/20 at 23:09:34, ojan wrote:
> bikeshed: I don't know that it makes sense to use chrome style within
directories that are already blink style. My vote would be to move directories
at a time. But...I don't feel too strongly.

Yeah, I agree.  Everything in the custom2 directory is in Chromium style.  I'll
delete the old custom directory once this CL lands.

[abarth-chromium, 2015-02-21 00:15:46]

Committed patchset #2 (id:20001) manually as
2d2d1918a543b85e2c13134af4aee6d790f4c864 (presubmit successful).