Use HTMLMediaElement::togglePlayState() where appropriate

Use HTMLMediaElement::togglePlayState() where appropriate

togglePlayState() handles the MediaController case correctly, which the
updated code paths did not.

Introduce togglePlayStateWillPlay() to replace canPlay() and paused() in
certain contexts. The readyState < HAVE_METADATA in canPlay() condition
is not replicated because the hasSource() checks in paintMediaPlayButton
and paintMediaOverlayPlayButton disables the buttons so that they can't
be pressed at all. Some corner case seems likely to exist, but was not
found in ad-hoc testing.

Drop the ASSERT(controls()) in tooglePlayState() since it is now used in
contexts not directly tied to MediaControls. The ASSERT doesn't fail
yet, but the same ASSERT in togglePlayStateWillPlay() would, since
MediaControlPlayButtonElement::updateDisplayType() is called when the
controls are created for text track rendering but are not shown.

These changes made it possible to reduce the size of
MediaControllerInterface a little bit more.

BUG=341813
TEST=none, no observable changes intended

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=170296

[philipj_slow, 2014-03-27 17:26:52]

PTAL. For a CL of this size I'd like to have produced some new tests, but I
couldn't see anything that actually seemed worth testing. Please point out if
there's something I've overlooked.

The name "togglePlayStateWillPlay" is a bit awkward/non-obvious in a few
contexts where togglePlayState() isn't called, so if there's a better name I'm
open to suggestions!

[acolwell GONE FROM CHROMIUM, 2014-03-28 01:02:52]

lgtm % nit

https://codereview.chromium.org/214793005/diff/1/Source/core/html/HTMLMediaEl...
File Source/core/html/HTMLMediaElement.h (right):

https://codereview.chromium.org/214793005/diff/1/Source/core/html/HTMLMediaEl...
Source/core/html/HTMLMediaElement.h:160: bool togglePlayStateWillPlay() const;
nit: How about togglePlayStateWillTriggerPlay() or a descriptive comment here
that indiciates something similar.

[philipj_slow, 2014-03-28 07:22:23]

https://codereview.chromium.org/214793005/diff/1/Source/core/html/HTMLMediaEl...
File Source/core/html/HTMLMediaElement.h (right):

https://codereview.chromium.org/214793005/diff/1/Source/core/html/HTMLMediaEl...
Source/core/html/HTMLMediaElement.h:160: bool togglePlayStateWillPlay() const;
On 2014/03/28 01:02:52, acolwell wrote:
> nit: How about togglePlayStateWillTriggerPlay() or a descriptive comment here
> that indiciates something similar.

I added a comment to explain briefly what these two functions are for, I hope
that's better.

[philipj_slow, 2014-03-28 07:22:53]

The CQ bit was checked by philipj@opera.com

[commit-bot: I haz the power, 2014-03-28 07:22:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/philipj@opera.com/214793005/20001

[commit-bot: I haz the power, 2014-03-28 08:24:00]

Change committed as 170296