Add support for new accessibility roles from WebKit, with tests.

Add support for new accessibility roles from WebKit, with tests.

These roles worked before, but the code is now cleaner because
they directly correspond to a WebKit role, rather than requiring
matching on the tag name:
div, form, hr, label, p, presentational, spinbuttonpart

These roles bring new support for roles that were not previously
accessible:
canvas, spinbutton, togglebutton.

All of the interesting cases have new tests (content_browsertest target).

BUG=145346, 143689
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=156272

[dmazzoni, 2012-09-07 20:27:00]

aboxhall: primary review
dtseng: FYI / review welcome

piman: OWNERS rubberstamp

[piman, 2012-09-07 21:19:32]

owner LGTM+nit

http://codereview.chromium.org/10919157/diff/1/content/renderer/accessibility...
File content/renderer/accessibility_node_serializer.cc (right):

http://codereview.chromium.org/10919157/diff/1/content/renderer/accessibility...
content/renderer/accessibility_node_serializer.cc:401: //  dst->role =
AccessibilityNodeData::ROLE_CANVAS_WITH_FALLBACK_CONTENT;
Nit: remove commented code

[aboxhall, 2012-09-11 04:24:42]

LGTM
Looks fine to me, just a few things I'm curious about.

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/canvas-expected-mac.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/canvas-expected-mac.txt:1: Need to generate
When will this get generated?

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/canvas-expected-win.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/canvas-expected-win.txt:3: ROLE_SYSTEM_GRAPHIC
So read-only canvas doesn't show up as canvas role?

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/togglebutton-expected-win.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/togglebutton-expected-win.txt:4:
ROLE_SYSTEM_TEXT name='Toggle button' READONLY
Why does the toggle button role mean that the internal text gets exposed like
this, as well as in the name?

[dmazzoni, 2012-09-11 09:14:42]

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/canvas-expected-mac.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/canvas-expected-mac.txt:1: Need to generate
On 2012/09/11 04:24:42, aboxhall wrote:
> When will this get generated?

I'll do it in a separate changelist sometime. It's not as interesting for many
of these roles.

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/canvas-expected-win.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/canvas-expected-win.txt:3: ROLE_SYSTEM_GRAPHIC
On 2012/09/11 04:24:42, aboxhall wrote:
> So read-only canvas doesn't show up as canvas role?

Yeah, the idea is that some people treat canvas just like an image, i.e.

  <canvas alt="User icon" width=128 height=128><canvas>

In this case, it might make sense for the screen reader to call it a "graphic"
or "image" with alt text. For example, there's often a key to jump to the next
graphic or provide your own label for a graphic, or perform OCR on a graphic -
but nothing equivalent for a canvas. But when it has interactive content, it's a
group for screen readers that don't understand the Canvas role, otherwise it's a
canvas.

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
File content/test/data/accessibility/togglebutton-expected-win.txt (right):

http://codereview.chromium.org/10919157/diff/1/content/test/data/accessibilit...
content/test/data/accessibility/togglebutton-expected-win.txt:4:
ROLE_SYSTEM_TEXT name='Toggle button' READONLY
On 2012/09/11 04:24:42, aboxhall wrote:
> Why does the toggle button role mean that the internal text gets exposed like
> this, as well as in the name?

It's arbitrary. What really mattes is that it's exposed in the item that's
actually focusable.

[commit-bot: I haz the power, 2012-09-12 06:43:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/dmazzoni@chromium.org/10919157/3003

[commit-bot: I haz the power, 2012-09-12 10:31:53]

Change committed as 156272