Add content public APIs for Presentation API.

Add content public APIs for Presentation API.

The pieces added are as follows:

1. PresentationServiceDelegate: An interface to be implemented by an
embedder to handle Presentation API requests. Includes an Observer
interface to observe the lifetime of the delegate object.
2. PresentationScreenAvailabilityListener: An interface to be
implemented by content/ code to receive screen availability results
from the embedder.
3. Added method to ContentBrowserClient: GetPresentationServiceDelegate.
Returns nullptr by default. Embedder may override it with an
implementation that can handle Presentation API requests. Added to
allow content/ code to obtain a reference to a
PresentationServiceDelegate to forward presentation API requests to.

Presentation Mojo service patch: crrev.com/839773002/
Blink plumbing: crrev.com/832263007

The Chrome implementation of PresentationServiceDelegate is currently
in a private repo.

BUG=412331
Committed: https://crrev.com/11c9dde535c6b288d6a65f2ee5dfc0efd6a970d4
Cr-Commit-Position: refs/heads/master@{#313563}

[imcheng, 2015-01-28 00:25:05]

Patchset #1 (id:1) has been deleted

[imcheng, 2015-01-28 00:35:09]

imcheng@chromium.org changed reviewers:
+ avi@chromium.org, imcheng@chromium.org

[imcheng, 2015-01-28 00:35:10]

Hi Avi,

Please review everything in this patch. It contains purely
content/public/browser changes. Anton and our team is currently implementing
support for Presentation API (http://w3c.github.io/presentation-api/) and this
is the basic set of APIs we are exposing to enable content/ code to interact
with the embedder to handle the request (e.g. Media Router).

I currently have a working prototype for Chrome as an embedder in a private
repo. If you would like to see it or would like additional context to proveed
with the review, I would be more than happy to show you.

Thank you!

[imcheng, 2015-01-28 00:35:45]

imcheng@chromium.org changed reviewers:
- imcheng@chromium.org

[Avi (use Gerrit), 2015-01-28 01:02:49]

Minor nits to the design, but nothing huge.

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
File content/public/browser/presentation_screen_availability_listener.h (right):

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:13: //
asscociated with a presentation URL from an embedder.
typo: associated

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:28:
std::string presentation_url_;
Why this string and the accessor above? Why can't you make this a clean
observer-type class like you are doing with
PresentationServiceDelegate::Observer?

[imcheng, 2015-01-28 01:37:23]

imcheng@chromium.org changed reviewers:
+ imcheng@chromium.org

[imcheng, 2015-01-28 01:37:24]

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
File content/public/browser/presentation_screen_availability_listener.h (right):

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:13: //
asscociated with a presentation URL from an embedder.
On 2015/01/28 01:02:49, Avi wrote:
> typo: associated

Done.

https://codereview.chromium.org/883953002/diff/20001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:28:
std::string presentation_url_;
On 2015/01/28 01:02:49, Avi wrote:
> Why this string and the accessor above? Why can't you make this a clean
> observer-type class like you are doing with
> PresentationServiceDelegate::Observer?

That is because each PresentationScreenAvailabilityListener is tied to a
presentation URL. I changed it to have a GetPresentationUrl() pure virtual
function instead of the field and accessor. What do you think?

[Avi (use Gerrit), 2015-01-28 02:32:49]

Almost there. I want to keep the API layer as clean as possible.

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
File content/public/browser/presentation_screen_availability_listener.h (right):

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:18: :
presentation_url_(presentation_url) {}
How does this compile? presentation_url_ doesn't exist.

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:24: // Called
when screen availability for |presentation_url_| has changed to
presentation_url_ doesn't exist.

[Avi (use Gerrit), 2015-01-28 02:33:04]

Also, where are your tryjobs?

[imcheng, 2015-01-28 18:00:39]

Thanks. Launched try jobs just now.

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
File content/public/browser/presentation_screen_availability_listener.h (right):

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:18: :
presentation_url_(presentation_url) {}
On 2015/01/28 02:32:49, Avi wrote:
> How does this compile? presentation_url_ doesn't exist.

Removed. My bad, I forgot to try to compile it yesterday.

https://codereview.chromium.org/883953002/diff/40001/content/public/browser/p...
content/public/browser/presentation_screen_availability_listener.h:24: // Called
when screen availability for |presentation_url_| has changed to
On 2015/01/28 02:32:49, Avi wrote:
> presentation_url_ doesn't exist.

Done.

[Avi (use Gerrit), 2015-01-28 18:05:58]

lgtm

Looks good.

[imcheng, 2015-01-28 18:45:47]

The CQ bit was checked by imcheng@chromium.org

[commit-bot: I haz the power, 2015-01-28 18:47:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/883953002/60001

[commit-bot: I haz the power, 2015-01-28 19:43:59]

Committed patchset #3 (id:60001)

[commit-bot: I haz the power, 2015-01-28 19:45:50]

Patchset 3 (id:??) landed as
https://crrev.com/11c9dde535c6b288d6a65f2ee5dfc0efd6a970d4
Cr-Commit-Position: refs/heads/master@{#313563}