Revert of Enable iPad Tab Switcher by default on iOS.

Revert of Enable iPad Tab Switcher by default on iOS. (patchset #3 id:200001 of https://codereview.chromium.org/1725533004/ )

Reason for revert:
Broke iOS UI tests downstream.

Original issue's description:
> Enable iPad Tab Switcher by default on iOS.
>
> Enabling the Tab Switcher by default required fixing the
> snapshot_cache unittests.
>
> In turn, this required fixing/cleaning the snapshot_cache:
> -Always register/deregister for notifications.
> -Centralize the logic to use a LRU cache.
> -Centralize the logic to use an in-memory cache.
>
> Other changes:
> -Replaced msarda with jif in OWNERS
> -Trigger memory warning instead of calling |handleLowMemory| from tests.
>
> BUG=None
>
> Committed: https://crrev.com/7bc8524f4e0b9fa3a7758a81f195a0228196b8d4
> Cr-Commit-Position: refs/heads/master@{#377570}

TBR=sdefresne@chromium.org,jbbegue@chromium.org,jif@google.com,jif@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Committed: https://crrev.com/01585070827f2015e350af60355eeb63b2281b35
Cr-Commit-Position: refs/heads/master@{#378098}

[rohitrao (ping after 24h), 2016-02-27 02:09:02]

Created Revert of Enable iPad Tab Switcher by default on iOS.

[commit-bot: I haz the power, 2016-02-27 02:11:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1740353002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1740353002/1

[commit-bot: I haz the power, 2016-02-27 02:32:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1740353002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1740353002/1

[commit-bot: I haz the power, 2016-02-27 03:03:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1740353002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1740353002/1

[commit-bot: I haz the power, 2016-02-27 03:18:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-02-27 03:19:15]

Description was changed from

==========
Revert of Enable iPad Tab Switcher by default on iOS. (patchset #3 id:200001 of
https://codereview.chromium.org/1725533004/ )

Reason for revert:
Broke iOS UI tests downstream.

Original issue's description:
> Enable iPad Tab Switcher by default on iOS.
> 
> Enabling the Tab Switcher by default required fixing the
> snapshot_cache unittests.
> 
> In turn, this required fixing/cleaning the snapshot_cache:
> -Always register/deregister for notifications.
> -Centralize the logic to use a LRU cache.
> -Centralize the logic to use an in-memory cache.
> 
> Other changes:
> -Replaced msarda with jif in OWNERS
> -Trigger memory warning instead of calling |handleLowMemory| from tests.
> 
> BUG=None
> 
> Committed: https://crrev.com/7bc8524f4e0b9fa3a7758a81f195a0228196b8d4
> Cr-Commit-Position: refs/heads/master@{#377570}

TBR=sdefresne@chromium.org,jbbegue@chromium.org,jif@google.com,jif@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None
==========

to

==========
Revert of Enable iPad Tab Switcher by default on iOS. (patchset #3 id:200001 of
https://codereview.chromium.org/1725533004/ )

Reason for revert:
Broke iOS UI tests downstream.

Original issue's description:
> Enable iPad Tab Switcher by default on iOS.
>
> Enabling the Tab Switcher by default required fixing the
> snapshot_cache unittests.
>
> In turn, this required fixing/cleaning the snapshot_cache:
> -Always register/deregister for notifications.
> -Centralize the logic to use a LRU cache.
> -Centralize the logic to use an in-memory cache.
>
> Other changes:
> -Replaced msarda with jif in OWNERS
> -Trigger memory warning instead of calling |handleLowMemory| from tests.
>
> BUG=None
>
> Committed: https://crrev.com/7bc8524f4e0b9fa3a7758a81f195a0228196b8d4
> Cr-Commit-Position: refs/heads/master@{#377570}

TBR=sdefresne@chromium.org,jbbegue@chromium.org,jif@google.com,jif@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=None

Committed: https://crrev.com/01585070827f2015e350af60355eeb63b2281b35
Cr-Commit-Position: refs/heads/master@{#378098}
==========

[commit-bot: I haz the power, 2016-02-27 03:19:16]

Patchset 1 (id:??) landed as
https://crrev.com/01585070827f2015e350af60355eeb63b2281b35
Cr-Commit-Position: refs/heads/master@{#378098}

[sdefresne, 2016-02-29 09:11:35]

lgtm