Presentation API: allow the Mojo service to reject a getAvailability() call.

Presentation API: allow the Mojo service to reject a getAvailability() call.

This CL only does the Chromium/Blink glue and expose a Mojo signal that can
be used in order to inform the renderer process (thus Blink) that
getAvailability() isn't supported.

A future CL will use that plumbing for low memory devices on Android.

BUG=507295
Committed: https://crrev.com/f2c02c3f6c24b27407bb513d03029e39970a938b
Cr-Commit-Position: refs/heads/master@{#337832}

[mlamouri (slow - plz ping), 2015-07-06 17:49:29]

mlamouri@chromium.org changed reviewers:
+ avayvod@chromium.org

[whywhat, 2015-07-06 18:27:19]

https://codereview.chromium.org/1219273003/diff/1/content/common/presentation...
File content/common/presentation/presentation_service.mojom (right):

https://codereview.chromium.org/1219273003/diff/1/content/common/presentation...
content/common/presentation/presentation_service.mojom:117: // Called when the
client tries to listen for screen availability changes but
nit: Rephrase as

"Called when the client starts listening for screen availability and passive
availability monitoring is not supported by the device either permanently
(hardware limitations) or temporarily (battery saver mode)."

Should we indicate if the limitation is temporarily or not so the page/Blink
layer could try again depending on battery status, for example?

https://codereview.chromium.org/1219273003/diff/1/content/common/presentation...
content/common/presentation/presentation_service.mojom:123: // Called when the
client is listening for screen availability and the state
nit: "Called immediately when the client starts listening for screen
availability if the current availability state is known and later to notify the
client of the state updates."

[whywhat, 2015-07-06 18:27:23]

lgtm

[mlamouri (slow - plz ping), 2015-07-07 16:09:53]

The CQ bit was checked by mlamouri@chromium.org

[commit-bot: I haz the power, 2015-07-07 16:10:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1219273003/1

[commit-bot: I haz the power, 2015-07-07 16:26:19]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-07-07 16:26:20]

Try jobs failed on following builders:
  cast_shell_linux on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/cast_shell_linu...)
  linux_chromium_gn_chromeos_rel on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)
  mac_chromium_rel_ng on tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/mac_chromium_rel_...)

(exceeded global retry quota)

[mlamouri (slow - plz ping), 2015-07-08 14:06:33]

The CQ bit was checked by mlamouri@chromium.org

[mlamouri (slow - plz ping), 2015-07-08 14:06:33]

The patchset sent to the CQ was uploaded after l-g-t-m from avayvod@chromium.org
Link to the patchset: https://codereview.chromium.org/1219273003/#ps20001
(title: "update unit tests")

[commit-bot: I haz the power, 2015-07-08 14:06:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1219273003/20001

[commit-bot: I haz the power, 2015-07-08 16:23:13]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-07-08 16:24:12]

Patchset 2 (id:??) landed as
https://crrev.com/f2c02c3f6c24b27407bb513d03029e39970a938b
Cr-Commit-Position: refs/heads/master@{#337832}