Attempt to fix flaky ChromeOS test timeouts.

Attempt to fix flaky ChromeOS test timeouts.

Bisecting the UserAddingScreenTest.ScreenVisibility test timeouts
seems to have identified the causing CL.

This reverts the causing CL

4c6917e303938f0be7beb244abdfbf4723c2162f -- "cc:: Remove SwapAck throttling from Scheduler."

and enables tests again:

reverts 497a57a9b9c372cd58e3e1261d79916e4ca247c2 -- "Disable flaky timeout InlineLoginUIBrowserTest.DifferentStorageId on linux"
reverts ffc3747adcd49ca0185670dd6bc78078b4721544 -- "Disable WebViewAPITest.AcceptTouchEvents on Linux."
reverts efbbf859cec94c1a8d671499d190158fbdce3599 -- "Disabling UserImageManagerTest.SaveUserImageFromProfileImage.".
reverts f827c03bbf5971e2f24e32bd90ce4c40f5ee8f1c -- "Disable SharedOptionsTest.ScreenLockPreferencePrimary."
reverts 6e402f141ae341c5df18ca81e892089c47fae54f -- "Disable PreferencesTest.MultiProfiles."
reverts d65f70589ef04c62678b3e96d674689cbd3fd0c2 -- "Disable NetworkPortalDetectorImplBrowserTest.InSessionDetection."

BUG=423332, 423094, 423077, 423053, 423015, 422998, 422868
TBR=orglofch

Committed: https://crrev.com/0c972cb5f080fff7b82b86a4445f0faa4393bbc2
Cr-Commit-Position: refs/heads/master@{#299468}

[kustermann, 2014-10-14 12:52:59]

The CQ bit was checked by kustermann@google.com

[commit-bot: I haz the power, 2014-10-14 12:53:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/655783002/1

[commit-bot: I haz the power, 2014-10-14 13:06:37]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-14 13:07:31]

Patchset 1 (id:??) landed as
https://crrev.com/0c972cb5f080fff7b82b86a4445f0faa4393bbc2
Cr-Commit-Position: refs/heads/master@{#299468}