chrome.audio API: treat mute as system wide property

chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=680358
Review-Url: https://codereview.chromium.org/2578473002
Cr-Commit-Position: refs/heads/master@{#446592}
Committed: https://chromium.googlesource.com/chromium/src/+/7cb7db5ae23a21d9267ce2e707a7eb6a1389e66e

[tbarzic, 2016-12-14 02:58:06]

The CQ bit was checked by tbarzic@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-14 02:58:49]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-14 03:17:13]

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

[commit-bot: I haz the power, 2016-12-14 03:17:13]

Dry run: Try jobs failed on following builders:
  linux_chromium_chromeos_rel_ng on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[tbarzic, 2016-12-15 02:31:23]

The CQ bit was checked by tbarzic@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-15 02:31:38]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-15 02:37:42]

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

[commit-bot: I haz the power, 2016-12-15 02:37:43]

Dry run: Try jobs failed on following builders:
  win_clang on master.tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_clang/builds/...)

[tbarzic, 2016-12-21 02:01:30]

Description was changed from

==========
chrome.audio API: treat mute as system wide property

BUG=673392
==========

to

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Persisting per device mute is nit consistent between input and output 
  devices - input mute is not persisted in local state, unlike output 
  device mute; which mean setting mute state on an inactive input
  device is no-op.
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

The mute state is not persisted in local state to disable kiosk app 
from affecting regular users sessions - kiosk app should keep track of
state of audio devices it handles instead of relying on Chrome's local
state (arguably the same should be done for volume values).

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=673392
==========

[tbarzic, 2016-12-21 03:57:57]

The CQ bit was checked by tbarzic@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-21 03:58:10]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-21 05:10:21]

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

[commit-bot: I haz the power, 2016-12-21 05:10:22]

Dry run: This issue passed the CQ dry run.

[tbarzic, 2016-12-21 20:03:00]

Description was changed from

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Persisting per device mute is nit consistent between input and output 
  devices - input mute is not persisted in local state, unlike output 
  device mute; which mean setting mute state on an inactive input
  device is no-op.
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

The mute state is not persisted in local state to disable kiosk app 
from affecting regular users sessions - kiosk app should keep track of
state of audio devices it handles instead of relying on Chrome's local
state (arguably the same should be done for volume values).

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=673392
==========

to

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=673392
==========

[tbarzic, 2016-12-21 20:07:53]

The CQ bit was checked by tbarzic@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-21 20:08:29]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[tbarzic, 2016-12-21 20:41:47]

tbarzic@chromium.org changed reviewers:
+ jennyz@chromium.org

[tbarzic, 2016-12-21 20:41:48]

Please take a look - note that I'm missing an owner for audio.idl, I'll deffer
adding him until you take a look :)

[commit-bot: I haz the power, 2016-12-21 21:22:21]

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

[commit-bot: I haz the power, 2016-12-21 21:22:21]

Dry run: This issue passed the CQ dry run.

[tbarzic, 2016-12-22 01:29:56]

https://codereview.chromium.org/2578473002/diff/100001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/100001/extensions/common/api/...
extensions/common/api/audio.idl:144: [deprecated="Use
$(ref:onMuteStateChanged)."]
Do you know if this one is used at all - it doesn't seem to be according to
Chrome UMA?

[tbarzic, 2016-12-29 03:39:46]

The CQ bit was checked by tbarzic@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-12-29 03:39:52]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-12-29 04:29:30]

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

[commit-bot: I haz the power, 2016-12-29 04:29:31]

Dry run: This issue passed the CQ dry run.

[jennyz, 2017-01-10 00:47:26]

jennyz@chromium.org changed reviewers:
+ mnilsson@chromium.org

[jennyz, 2017-01-10 00:47:53]

+mnilsson@ for review.

https://codereview.chromium.org/2578473002/diff/100001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/100001/extensions/common/api/...
extensions/common/api/audio.idl:144: [deprecated="Use
$(ref:onMuteStateChanged)."]
On 2016/12/22 01:29:56, tbarzic wrote:
> Do you know if this one is used at all - it doesn't seem to be according to
> Chrome UMA?

Better ask mnilsson.

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
File extensions/browser/api/audio/audio_service_chromeos.cc (right):

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:195: return false;
Combined into one line, no need to use bool found. Problem with original code,
but please fix it now.

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:206: if (is_input) {
Don't need "{" for one line if or else block.

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:219: if (is_input) {
ditto

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:46: StreamType streamType;
Changing the existing protocol might break the old client. Have you tested if
this will still be compatible with the old client?

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:115: //     stream type.
No need to indent 4 spaces in the above line.

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:139: static void onMuteChanged(MuteChangedEvent
event);
This changed the existing event's protocol. This may break the existing client.

[tbarzic, 2017-01-11 00:47:03]

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
File extensions/browser/api/audio/audio_service_chromeos.cc (right):

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:195: return false;
On 2017/01/10 00:47:53, jennyz wrote:
> Combined into one line, no need to use bool found. Problem with original code,
> but please fix it now.

Done.

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:206: if (is_input) {
On 2017/01/10 00:47:53, jennyz wrote:
> Don't need "{" for one line if or else block.

Done.

https://codereview.chromium.org/2578473002/diff/160001/extensions/browser/api...
extensions/browser/api/audio/audio_service_chromeos.cc:219: if (is_input) {
On 2017/01/10 00:47:53, jennyz wrote:
> ditto

Done.

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:46: StreamType streamType;
On 2017/01/10 00:47:53, jennyz wrote:
> Changing the existing protocol might break the old client. Have you tested if
> this will still be compatible with the old client?

this one should be backward compatible - it's only used when the object is
returned from system - it should be safe to add a new property.

(and also, the event reporting this object does not seem to be utilized)

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:115: //     stream type.
On 2017/01/10 00:47:53, jennyz wrote:
> No need to indent 4 spaces in the above line.

Done.

https://codereview.chromium.org/2578473002/diff/160001/extensions/common/api/...
extensions/common/api/audio.idl:139: static void onMuteChanged(MuteChangedEvent
event);
On 2017/01/10 00:47:53, jennyz wrote:
> This changed the existing event's protocol. This may break the existing
client.

yes, that comes back to the question for which mnilsson is cc'ed :)
If the event isn't really in use, there's nothing to break, if it is, I'll add
(and mark deprecated) the old event.

[tbarzic, 2017-01-12 01:49:37]

Description was changed from

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=673392
==========

to

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=680358
==========

[jennyz, 2017-01-12 21:53:03]

I saw your reply to my comments, but no the new patch with changes. Have you
forgotten to upload the patch?

[tbarzic, 2017-01-12 21:58:49]

oh, I must have - it's uploaded now :)

[jennyz, 2017-01-18 00:53:05]

lgtm

[tbarzic, 2017-01-19 01:31:15]

tbarzic@chromium.org changed reviewers:
+ isherman@chromium.org, rdevlin.cronin@chromium.org

[tbarzic, 2017-01-19 01:31:16]

adding owners:
isherman: histograms
rdevlin.cronin: audio.idl

[Ilya Sherman, 2017-01-19 01:58:57]

histograms.xml lgtm

[Devlin, 2017-01-25 16:12:24]

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:45: // Stream type associated with this device
(input or output).
nit: given we specify what StreamType can be above, we shouldn't have (input or
output) here.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:91: // Type of the stream for which mute value
has changed. The updated mute
nitty nit:
The type of the stream for which the mute value changed. The updated...

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:95: // Value to which mute state changed.
nitty nit:
Whether or not the stream is now muted

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:96: boolean value;
|value| is a little less descriptive than something like "isMuted"

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:139: EmptyCallback callback);
can this be an optional callback?

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:154: static void onMuteChanged(MuteChangedEvent
event);
Are we okay with this breaking change since this API isn't publicly available? 
If so, can we just remove the [deprecated=] properties above?

[tbarzic, 2017-01-25 19:32:29]

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:45: // Stream type associated with this device
(input or output).
On 2017/01/25 16:12:24, Devlin (catching up) wrote:
> nit: given we specify what StreamType can be above, we shouldn't have (input
or
> output) here.

Done.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:91: // Type of the stream for which mute value
has changed. The updated mute
On 2017/01/25 16:12:23, Devlin (catching up) wrote:
> nitty nit:
> The type of the stream for which the mute value changed. The updated...

Done.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:95: // Value to which mute state changed.
On 2017/01/25 16:12:23, Devlin (catching up) wrote:
> nitty nit:
> Whether or not the stream is now muted

Done.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:96: boolean value;
On 2017/01/25 16:12:23, Devlin (catching up) wrote:
> |value| is a little less descriptive than something like "isMuted"

Done.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:139: EmptyCallback callback);
On 2017/01/25 16:12:23, Devlin (catching up) wrote:
> can this be an optional callback?

Done.

https://codereview.chromium.org/2578473002/diff/240001/extensions/common/api/...
extensions/common/api/audio.idl:154: static void onMuteChanged(MuteChangedEvent
event);
On 2017/01/25 16:12:23, Devlin (catching up) wrote:
> Are we okay with this breaking change since this API isn't publicly available?

> If so, can we just remove the [deprecated=] properties above?

We are OK with this because the event doesn't seem to be used for now (no entry
in event histograms, also nothing turns up in the code search).

Items marked deprecated are in use - note that I plan to make those nodoc when
the API goes stable.

[Devlin, 2017-01-25 21:35:04]

audio.idl lgtm with nits

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:51: // "AOKR", and "OTHER".
unrelated to this CL, but can you file a bug to make deviceType an enum?

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:127: // Gets system-wide mute state for the
specified stream type.
nitty nit: Gets *the* system-wide...

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:135: // |streamType|: Stream type for which mute
status should be set.
nitty nit: s/status/state for consistency

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:136: // |value|: New mute value.
here, too, s/value/isMuted

[tbarzic, 2017-01-25 22:35:49]

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
File extensions/common/api/audio.idl (right):

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:51: // "AOKR", and "OTHER".
On 2017/01/25 21:35:03, Devlin (catching up) wrote:
> unrelated to this CL, but can you file a bug to make deviceType an enum?

I had something like that in mind too - created a bug:
https://bugs.chromium.org/p/chromium/issues/detail?id=685382

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:127: // Gets system-wide mute state for the
specified stream type.
On 2017/01/25 21:35:04, Devlin (catching up) wrote:
> nitty nit: Gets *the* system-wide...

Done.

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:135: // |streamType|: Stream type for which mute
status should be set.
On 2017/01/25 21:35:04, Devlin (catching up) wrote:
> nitty nit: s/status/state for consistency

Done.

https://codereview.chromium.org/2578473002/diff/260001/extensions/common/api/...
extensions/common/api/audio.idl:136: // |value|: New mute value.
On 2017/01/25 21:35:04, Devlin (catching up) wrote:
> here, too, s/value/isMuted

Done.

[tbarzic, 2017-01-25 22:55:19]

The CQ bit was checked by tbarzic@chromium.org

[tbarzic, 2017-01-25 22:55:20]

The patchset sent to the CQ was uploaded after l-g-t-m from jennyz@chromium.org,
isherman@chromium.org, rdevlin.cronin@chromium.org
Link to the patchset: https://codereview.chromium.org/2578473002/#ps300001
(title: ".")

[commit-bot: I haz the power, 2017-01-25 22:55:57]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-26 02:13:39]

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

[commit-bot: I haz the power, 2017-01-26 02:13:40]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[tbarzic, 2017-01-26 02:18:37]

The CQ bit was checked by tbarzic@chromium.org

[commit-bot: I haz the power, 2017-01-26 02:19:33]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-26 05:25:14]

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

[commit-bot: I haz the power, 2017-01-26 05:25:15]

Try jobs failed on following builders:
  linux_android_rel_ng on master.tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[tbarzic, 2017-01-27 02:27:07]

The CQ bit was checked by tbarzic@chromium.org

[commit-bot: I haz the power, 2017-01-27 02:27:45]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-27 04:30:49]

CQ is committing da patch.

Bot data: {"patchset_id": 300001, "attempt_start_ts": 1485484027418270,
"parent_rev": "c8184a6cb8dd16ca649f3a6b074cbc03bfed0b72", "commit_rev":
"7cb7db5ae23a21d9267ce2e707a7eb6a1389e66e"}

[commit-bot: I haz the power, 2017-01-27 04:31:36]

Description was changed from

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=680358
==========

to

==========
chrome.audio API: treat mute as system wide property

As part of audio API cleanup, simplify handling of mute flag.
Current implementation has few problems:
* Setting/getting mute state is done per device, even though mute is
  system property (on the other hand mute state listeners are not
  bound to a specific device).
* Muting input or output is not intuitive - one would have to
  find an active device and set it's mute property - this would also
  set mute for all remaining active devices.

This CL fixes these problems by decoupling mute state setter/getter
from particular device properties, and bounding states to stream type.

Additionally, StreamType enum is introduced - the type specifies type
of stream an audio device supports (input or output) and is intended
to replace existing isInput booleans used across the API.

Existing methods for managing mute state are kept around, but will not
be exposed to stable channel once the API is opened up (modulo 
current API whitelist).

BUG=680358

Review-Url: https://codereview.chromium.org/2578473002
Cr-Commit-Position: refs/heads/master@{#446592}
Committed:
https://chromium.googlesource.com/chromium/src/+/7cb7db5ae23a21d9267ce2e707a7...
==========

[commit-bot: I haz the power, 2017-01-27 04:31:37]

Committed patchset #16 (id:300001) as
https://chromium.googlesource.com/chromium/src/+/7cb7db5ae23a21d9267ce2e707a7...