Revert of cc: Test BeginMainFrame values come from BeginImplFrame.

Revert of cc: Test BeginMainFrame values come from BeginImplFrame. (patchset #2 id:20001 of https://codereview.chromium.org/1104193003/)

Reason for revert:
LayerTreeHostTestBeginMainFrameTimeIsAlsoImplTime started failing since a dependent patch (https://codereview.chromium.org/787763006/) is reverted.

example:
https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests/builds/24421

Original issue's description:
> cc: Test BeginMainFrame values come from BeginImplFrame.
>
> The frame time in the BeginFrameArgs sent to BeginMainFrame should match a
> value from a BeginImplFrame. However there is not a 1:1 relantionship, when the
> main thread is slow, there many be multiple impl frames.
>
> DEPS=http://crrev.com/787763006
> BUG=346230
> R=brianderson,enne
>
> Committed: https://crrev.com/a003f9bc651a572fea3881cfb72a7d8842c62192
> Cr-Commit-Position: refs/heads/master@{#328929}

TBR=brianderson@chromium.org,enne@chromium.org,mithro@mithis.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=346230
Committed: https://crrev.com/2c7f34a4d97b466b25bb67eb0145036dcede6053
Cr-Commit-Position: refs/heads/master@{#328941}

[Kunihiko Sakamoto, 2015-05-08 09:57:35]

Created Revert of cc: Test BeginMainFrame values come from BeginImplFrame.

[commit-bot: I haz the power, 2015-05-08 09:57:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1133763002/1

[commit-bot: I haz the power, 2015-05-08 09:58:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-08 09:59:09]

Patchset 1 (id:??) landed as
https://crrev.com/2c7f34a4d97b466b25bb67eb0145036dcede6053
Cr-Commit-Position: refs/heads/master@{#328941}