Revert of cc: Call PrepareTiles when becoming visible in browser only.

Revert of cc: Call PrepareTiles when becoming visible in browser only. (patchset #4 id:60001 of https://codereview.chromium.org/1239843002/)

Reason for revert:
LayerTreeHostTestReadyToDrawVisibility times out under DrMemory: http://build.chromium.org/p/chromium.memory.fyi/builders/Windows%20Unit%20%28DrMemory%20full%29%20%285%29/builds/4546/steps/memory%20test%3A%20cc/logs/stdio

[----------] 2 tests from LayerTreeHostTestReadyToDrawVisibility
[ RUN      ] LayerTreeHostTestReadyToDrawVisibility.RunSingleThread_DirectRenderer
c:\b\build\slave\drm-cr\build\src\cc\test\layer_tree_test.cc(875): error: Failed
Test timed out
[  FAILED  ] LayerTreeHostTestReadyToDrawVisibility.RunSingleThread_DirectRenderer (5044 ms)
[ RUN      ] LayerTreeHostTestReadyToDrawVisibility.RunSingleThread_DelegatingRenderer
c:\b\build\slave\drm-cr\build\src\cc\test\layer_tree_test.cc(875): error: Failed
Test timed out
[  FAILED  ] LayerTreeHostTestReadyToDrawVisibility.RunSingleThread_DelegatingRenderer (5244 ms)
[----------] 2 tests from LayerTreeHostTestReadyToDrawVisibility (10292 ms total)

Original issue's description:
> cc: Call PrepareTiles when becoming visible in browser only.
>
> Calling PrepareTiles on each visibility change might have caused a v8
> idle time benchmark regression. We only need to call PrepareTiles for
> the SingleThreadProxy wait for ready to draw mode.
>
> R=brianderson@chromium.org,danakj@chromium.org
> TEST=LayerTreeHostTestReadyToDrawVisibility
> BUG=499040
> CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
>
> Committed: https://crrev.com/c67e9d831fa3753fc5434229d3275b1c0155edae
> Cr-Commit-Position: refs/heads/master@{#339201}

BUG=499040
Committed: https://crrev.com/e13101c1f51685c13c1a2f5bafa110027ef12d70
Cr-Commit-Position: refs/heads/master@{#339540}

[Jeffrey Yasskin, 2015-07-20 19:05:36]

Created Revert of cc: Call PrepareTiles when becoming visible in browser only.

[Jeffrey Yasskin, 2015-07-20 19:07:41]

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

[commit-bot: I haz the power, 2015-07-20 19:08:00]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1239363003/1

[commit-bot: I haz the power, 2015-07-20 20:34:45]

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

[commit-bot: I haz the power, 2015-07-20 20:34:45]

Dry run: This issue passed the CQ dry run.

[danakj, 2015-07-20 22:28:08]

LGTM

[Jeffrey Yasskin, 2015-07-20 22:28:39]

The CQ bit was checked by jyasskin@chromium.org

[commit-bot: I haz the power, 2015-07-20 22:28:58]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1239363003/1

[commit-bot: I haz the power, 2015-07-20 22:35:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-20 22:37:27]

Patchset 1 (id:??) landed as
https://crrev.com/e13101c1f51685c13c1a2f5bafa110027ef12d70
Cr-Commit-Position: refs/heads/master@{#339540}