Mark wrappers of canvas rendering context objects as dependent.

Mark wrappers of canvas rendering context objects as dependent.

When initially called, canvas.getContext() will return a fresh rendering
context object, but at the same time switch its "context mode" to a direct
one (2d or webgl), such that subsequent getContext() with the same
contextID argument will return that initially created context object.

To correctly provide that same-object identity, the wrapper object must be
marked as depending on the canvas element object, such that it will be
retained across GCs.

R=junov,haraken
BUG=450410
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192465

[sof, 2015-03-24 10:17:35]

sigbjornf@opera.com changed reviewers:
+ junov@chromium.org, kbr@chromium.org

[sof, 2015-03-24 10:17:36]

please take a look.

[haraken, 2015-03-24 10:33:17]

LGTM

[Justin Novosad, 2015-03-24 16:08:32]

lgtm with suggestion

https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
File LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html (right):

https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html:23: gc();
Just a suggestion, but you could go a step further here and set canvas to null
before gc(), and the re-get the canvas from the document.

[sof, 2015-03-24 16:14:23]

https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
File LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html (right):

https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html:23: gc();
On 2015/03/24 16:08:32, junov wrote:
> Just a suggestion, but you could go a step further here and set canvas to null
> before gc(), and the re-get the canvas from the document.

i.e., not use document.createElement()?

[sof, 2015-03-24 16:31:48]

On 2015/03/24 16:14:23, sof wrote:
>
https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
> File LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html (right):
> 
>
https://codereview.chromium.org/1033613002/diff/20001/LayoutTests/fast/canvas...
> LayoutTests/fast/canvas/webgl/context-gc-custom-properties.html:23: gc();
> On 2015/03/24 16:08:32, junov wrote:
> > Just a suggestion, but you could go a step further here and set canvas to
null
> > before gc(), and the re-get the canvas from the document.
> 
> i.e., not use document.createElement()?

fast/dom/gc-9.html and the webgl conformance test do test along those lines, so
i will leave the test as-is.

[sof, 2015-03-24 19:07:51]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-03-24 19:08:09]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1033613002/20001

[commit-bot: I haz the power, 2015-03-24 19:52:11]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192465

[Ken Russell (switch to Gerrit), 2015-03-24 22:02:10]

Thanks for this fix!