Get rid of multiple inheritence for SVGViewElement interface

Get rid of multiple inheritence for SVGViewElement interface

Web IDL no longer supports multiple inheritence. As per the latest
specification SVGViewElement should only inherit from SVGElement.
'implements' statements are used for the rest. This patch refactors
the IDL files to match the latest specification:
http://www.w3.org/TR/SVG2/linking.html#InterfaceSVGViewElement

Note that there is a WebExposed change as SVGZoomAndPan used to be
exposed on the Window and it is not anymore. SVGZoomAndPan merely
supplements SVGViewElement and should not be exposed to JavaScript
according to the latest specification.

BUG=251772
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=152827

[do-not-use, 2013-06-19 15:41:27]

Please note the change of behavior for SVGZoomAndPan. This is according to
specification but I don't know if this is OK.

If this is not acceptable, then I would have to get rid of [NoInterfaceObject]
for this interface and work on the bindings generator so that it generates the
JS*.* for "supplemental" interfaces without [NoInterfaceObject]. Right now, they
are not generated, similarly to partial interfaces.

[haraken, 2013-06-19 15:45:30]

schenney: Could you take a look? This is a change to make the Blink IDL
comformant to the spec and speed up the IDL compiler.

Christophe: You can create a crbug for this kind of non-trivial change so that
others can discuss the bug.

[do-not-use, 2013-06-19 15:55:41]

On 2013/06/19 15:45:30, haraken wrote:
> schenney: Could you take a look? This is a change to make the Blink IDL
> comformant to the spec and speed up the IDL compiler.
> 
> Christophe: You can create a crbug for this kind of non-trivial change so that
> others can discuss the bug.

Sorry about that, I filed Bug 251772.

[arv (Not doing code reviews), 2013-06-19 16:14:34]

LGTM

I think it is fine to remove the SVGZoomAndPan interface object.

[abarth-chromium, 2013-06-19 18:09:27]

https://codereview.chromium.org/16959011/diff/1/Source/core/svg/SVGFitToViewB...
File Source/core/svg/SVGFitToViewBox.idl (right):

https://codereview.chromium.org/16959011/diff/1/Source/core/svg/SVGFitToViewB...
Source/core/svg/SVGFitToViewBox.idl:34: SVGViewElement implements
SVGFitToViewBox;
Does this imply DoNotGenerateToV8?  I guess it would have to.

[Stephen Chennney, 2013-06-19 18:29:20]

The change seems fine in itself. I have some concerns about the broader impact.

Do we have any way of knowing what content will be broken by this? I know it's
reasonably obscure, and we didn't even support it until relatively recently, but
do we have any information on usage? Is there any way to do it that also
provides a back-compatibility path? I suspect there is nothing tractable, but I
would like confirmation.

We'll be facing similar issues with many SVG features. Can anyone add background
(maybe on the bug) as to how we typically deal with content-breaking spec
changes?

[do-not-use, 2013-06-20 11:07:12]

On 2013/06/19 18:29:20, Stephen Chenney wrote:
> The change seems fine in itself. I have some concerns about the broader
impact.
> 
> Do we have any way of knowing what content will be broken by this? I know it's
> reasonably obscure, and we didn't even support it until relatively recently,
but
> do we have any information on usage? Is there any way to do it that also
> provides a back-compatibility path? I suspect there is nothing tractable, but
I
> would like confirmation.
> 
> We'll be facing similar issues with many SVG features. Can anyone add
background
> (maybe on the bug) as to how we typically deal with content-breaking spec
> changes?

I cannot talk about usage. However, if we want backward-compatibility, the
less-costly way to do it would be to keep SVGZoomAndPan as a regular interface
(without [NoInterfaceObject] or implements statement) and then copy the content
of SVGZoomAndPan to SVGViewElement with a comment explaining that this should be
removed and SVGViewElement should implement SVGZoomAndPan instead.

This is very little extra work and it still gets rid of the multiple inheritance
while staying backward compatible. However, how do we discourage content to
start using the deprecated interface? How do developers know it is deprecated?
By reading the spec?

[do-not-use, 2013-06-20 11:33:03]

https://codereview.chromium.org/16959011/diff/1/Source/core/svg/SVGExternalRe...
File Source/core/svg/SVGExternalResourcesRequired.idl (left):

https://codereview.chromium.org/16959011/diff/1/Source/core/svg/SVGExternalRe...
Source/core/svg/SVGExternalResourcesRequired.idl:29: ] interface
SVGExternalResourcesRequired {
Also note that while I kept this interface for backward compatibility, this is
no longer part of the specification.

[Stephen Chennney, 2013-06-20 17:31:18]

Upon retrospect, I'm fine with it. LGTM

[commit-bot: I haz the power, 2013-06-20 17:31:50]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@sisa.samsung.com/16959011/1

[commit-bot: I haz the power, 2013-06-20 19:26:50]

Failed to apply patch for Source/core/core.gypi:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file Source/core/core.gypi
  Hunk #1 FAILED at 353.
  1 out of 2 hunks FAILED -- saving rejects to file Source/core/core.gypi.rej

Patch:       Source/core/core.gypi
Index: Source/core/core.gypi
diff --git a/Source/core/core.gypi b/Source/core/core.gypi
index
500c2072e92146cbd7342da5b040c4a0e30ab3e2..b1279651a4d9a522ab169a61592ac550062108da
100644
--- a/Source/core/core.gypi
+++ b/Source/core/core.gypi
@@ -353,6 +353,7 @@
             'svg/SVGElementInstanceList.idl',
             'svg/SVGEllipseElement.idl',
             'svg/SVGException.idl',
+            'svg/SVGExternalResourcesRequired.idl',
             'svg/SVGFEBlendElement.idl',
             'svg/SVGFEColorMatrixElement.idl',
             'svg/SVGFEComponentTransferElement.idl',
@@ -379,6 +380,7 @@
             'svg/SVGFETileElement.idl',
             'svg/SVGFETurbulenceElement.idl',
             'svg/SVGFilterElement.idl',
+            'svg/SVGFitToViewBox.idl',
             'svg/SVGFontElement.idl',
             'svg/SVGFontFaceElement.idl',
             'svg/SVGFontFaceFormatElement.idl',

[commit-bot: I haz the power, 2013-06-20 20:02:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ch.dumez@sisa.samsung.com/16959011/13002

[commit-bot: I haz the power, 2013-06-20 21:50:36]

Change committed as 152827