[Reland] Support listening for available screens for multiple

[Reland] Support listening for available screens for multiple
Presentation URLs on a per frame basis.

Reland of 906113002. Previously failed to build due to missing
CONTENT_EXPORTs which are added in this patch.

Tested locally by switching to building using shared_library, repro'ed
the problem, then added the CONTENT_EXPORT and built successfully.

Support listening for available screens for multiple
Presentation URLs on a per frame basis.

This is done by associating PresentationServiceImpl
with the RenderFrameHost. When Presentation API
requests are passed to PresentationServiceImpl, it
will delegate to the embedder's Media Router along
with the frame id via the PresentationServiceDelegate
interface.

Each PresentationServiceImpl also maintains a hash
map of Presentation URLs currently registered to
"context" objects. These objects wait for both result
and renderer (i.e. callback) to both be ready before
sending the result back to renderer /
PresentationDispatcher.

Furthermore, PresentationServiceImpl listens for
changes to the RenderFrameHost. If an out of page
navigation occurred or if RenderFrameHost is
being destroyed, all current Presentation URLs
are unregistered.

Also added unit tests for PresentationSerivceImpl.

BUG=412331
Committed: https://crrev.com/9f515d066350e9be283ae8a0a36a6cb29218d8de
Cr-Commit-Position: refs/heads/master@{#315624}

[imcheng, 2015-02-10 06:45:44]

imcheng@chromium.org changed reviewers:
+ avayvod@google.com, avi@chromium.org, imcheng@chromium.org

[imcheng, 2015-02-10 06:45:44]

Avi, Anton: PTAL again, thanks. Previous patch crrev.com/906113002 was reverted
due to linking error (Strangely this was not caught by the CQ). I added the
missing CONTENT_EXPORTs and verified locally.

[Avi (use Gerrit), 2015-02-10 15:41:03]

On 2015/02/10 06:45:44, imcheng1 wrote:
> Avi, Anton: PTAL again, thanks. Previous patch crrev.com/906113002 was
reverted
> due to linking error (Strangely this was not caught by the CQ). I added the
> missing CONTENT_EXPORTs and verified locally.

If the only difference is CONTENT_EXPORT, then LGTM.

And yeah, we don't have component trybots. It sucks.

[imcheng (use chromium acct), 2015-02-10 17:43:43]

New patchsets have been uploaded after l-g-t-m from avi@chromium.org

[imcheng, 2015-02-10 19:11:47]

The CQ bit was checked by imcheng@chromium.org

[commit-bot: I haz the power, 2015-02-10 19:12:26]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/887563006/40001

[commit-bot: I haz the power, 2015-02-10 20:09:35]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-10 20:10:31]

Patchset 3 (id:??) landed as
https://crrev.com/9f515d066350e9be283ae8a0a36a6cb29218d8de
Cr-Commit-Position: refs/heads/master@{#315624}