Implement ::content

Implement ::content

Existing: ::-webkit-distributed(parameter) -> New: ::content parameter

Example:
 - ::-webkit-distributed(div) -> ::content div
 - ::-webkit-distributed(> div) -> ::content > div

A W3C bug related to this implementation:
https://www.w3.org/Bugs/Public/show_bug.cgi?id=22829

::content is guarded by RuntimeEnabledFeatures::shadowDOMEnabled.

BUG=253655
TESTS=LayoutTests/fast/dom/shadow/content-pseudo-element-css-text.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-dynamic-attribute-change.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-for-shadow-element.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-match-all.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-match-descendant.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-nested.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-relative-selector-css-text.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-relative-selector.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-reprojection.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-scoped.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-specifiers-in-left-side.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-support-selector.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-used-in-selector-list.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element-with-any.html,
      LayoutTests/fast/dom/shadow/content-pseudo-element.html,
      LayoutTests/fast/dom/shadow/no-style-sharing-with-uncommon-attribute-and-pseudo-content.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=155512

[hayato, 2013-07-31 08:12:35]

We should implement this feature as an unprefixed API of '::content', rather
than reusing 'webkit-distributed()', and guard it with ShadowDOM flag.

[tasak, 2013-07-31 09:05:01]

On 2013/07/31 08:12:35, hayato wrote:
> We should implement this feature as an unprefixed API of '::content', rather
> than reusing 'webkit-distributed()', and guard it with ShadowDOM flag.

Please update crbug.com/253655.

[tasak, 2013-07-31 11:07:25]

On 2013/07/31 08:12:35, hayato wrote:
> We should implement this feature as an unprefixed API of '::content', rather
> than reusing 'webkit-distributed()', and guard it with ShadowDOM flag.

Done.
However, I have not added some layout test which uses both ::-webkit-distributed
and ::content in the same selector yet.

I'm not sure whether we really need such a test.

[dglazkov, 2013-07-31 20:05:17]

This looks relatively painless! Hayato-san, WDYT?

[hayato, 2013-08-01 02:34:29]

Could you guard '::content' by Shadow DOM flag?

I am not sure how to guard, but this might be helpful.
https://code.google.com/p/chromium/issues/detail?id=232181

https://codereview.chromium.org/21151005/diff/5002/Source/core/css/CSSParserV...
File Source/core/css/CSSParserValues.h (right):

https://codereview.chromium.org/21151005/diff/5002/Source/core/css/CSSParserV...
Source/core/css/CSSParserValues.h:215: bool relationIsForShadowDistributed()
const { return m_selector->relationIsForShadowDistributed(); }
Could you change the name of the relation?
Now it's '::content'. We might want to rename the relation so that it matches
the name of pseudo-elements.

[tasak, 2013-08-01 03:31:44]

Thank you for reviewing.

I have already guarded ::content, i.e.

         if (RuntimeEnabledFeatures::customDOMElementsEnabled())
             nameToPseudoType->set(unresolved.impl(),
CSSSelector::PseudoUnresolved);
+        if (RuntimeEnabledFeatures::shadowDOMEnabled())
+            nameToPseudoType->set(content.impl(), CSSSelector::PseudoContent);

If and only if shadowDOMEnabled, ::content is parsed as PseudoContent.

https://codereview.chromium.org/21151005/diff/5002/Source/core/css/CSSParserV...
File Source/core/css/CSSParserValues.h (right):

https://codereview.chromium.org/21151005/diff/5002/Source/core/css/CSSParserV...
Source/core/css/CSSParserValues.h:215: bool relationIsForShadowDistributed()
const { return m_selector->relationIsForShadowDistributed(); }
On 2013/08/01 02:34:29, hayato wrote:
> Could you change the name of the relation?
> Now it's '::content'. We might want to rename the relation so that it matches
> the name of pseudo-elements.

Done.

[hayato, 2013-08-01 03:37:56]

lgtm

Do you have a plan to remove '-webkit-distributed(..)' in the near future?
It's not healthy that we have a lot of similar Layout tests where the only
difference between them is the syntax of the selector.

[hayato, 2013-08-01 03:39:41]

Also you might want to mention that '::content' is guarded by the ShadowDOM flag
in the description.

[tasak, 2013-08-01 09:53:05]

On 2013/08/01 03:39:41, hayato wrote:
> Also you might want to mention that '::content' is guarded by the ShadowDOM
flag
> in the description.

Sure. Done.

[hayato, 2013-08-05 03:56:35]

Thank you. You can land this patch.

Could you file an issue to remove '::-webkit-distributed()' so that we don't
forget that?

[tasak, 2013-08-05 05:31:04]

On 2013/08/05 03:56:35, hayato wrote:
> Thank you. You can land this patch.
> 
> Could you file an issue to remove '::-webkit-distributed()' so that we don't
> forget that?

Sure. I have just filed a new isse, crbug.com/268236

[commit-bot: I haz the power, 2013-08-05 05:31:18]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/tasak@google.com/21151005/26001

[commit-bot: I haz the power, 2013-08-05 06:58:51]

Change committed as 155512