Move dispatchDidFirstVisuallyNonEmptyLayout into WebViewImpl.

Reland: Move dispatchDidFirstVisuallyNonEmptyLayout into WebViewImpl.

This removes a user of didLayoutWithPendingStylesheets() and instead moves
the call to dispatchDidFirstVisuallyNonEmptyLayout into WebViewImpl so the
notification to the embedder is tied to the pumping of frames. This changes the
behavior of this notification to only dispatch for the top level frame,
but Chromium already has a check for that:

https://chromium.googlesource.com/chromium/src/+/976d4d9a2735bdc11e5a641c84b6382566d48f1d/content/renderer/render_frame_impl.cc#3472

RenderFrameImpl::didFirstVisuallyNonEmptyLayout's first check is

if (frame->parent())
    return;

so we already ignore all frames that are not the main frame. Future patches will
clean up this interface so it's obvious this really only happens for the main
frame.

This was originally comitted as r200664, but got reverted due to making a test
flaky in Chromium that was depending on very specific timing of this callback.
That test was fixed by:
https://crrev.com/0ea17fce0d5218c909985e2216051eab79419463

BUG=521692
R=dglazkov@chromium.org

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200934

[esprehn, 2015-08-16 21:37:29]

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

[commit-bot: I haz the power, 2015-08-16 21:37:37]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295053002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295053002/20001

[commit-bot: I haz the power, 2015-08-16 22:32:39]

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

[commit-bot: I haz the power, 2015-08-16 22:32:40]

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

[esprehn, 2015-08-17 06:34:14]

esprehn@chromium.org changed reviewers:
+ dglazkov@chromium.org, ojan@chromium.org

[dglazkov, 2015-08-17 15:04:31]

On 2015/08/17 at 06:35:08, esprehn wrote:
> 

LGTM. Would love to have a meta bug for this type of work, so that we could
track all the amazing progress!

[esprehn, 2015-08-17 17:59:31]

The CQ bit was checked by esprehn@chromium.org

[esprehn, 2015-08-17 17:59:41]

On 2015/08/17 at 15:04:31, dglazkov wrote:
> On 2015/08/17 at 06:35:08, esprehn wrote:
> > 
> 
> LGTM. Would love to have a meta bug for this type of work, so that we could
track all the amazing progress!

Filed http://crbug.com/521692

[commit-bot: I haz the power, 2015-08-17 17:59:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295053002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295053002/20001

[esprehn, 2015-08-17 20:14:11]

Committed patchset #2 (id:20001) manually as 200664 (presubmit successful).

[esprehn, 2015-08-17 21:22:26]

A revert of this CL (patchset #2 id:20001) has been created in
https://codereview.chromium.org/1294683004/ by esprehn@chromium.org.

The reason for reverting is: Looks like it caused a race in:

ProfileErrorBrowserTestInstance/ProfileErrorBrowserTest.CorruptedProfile
.

[esprehn, 2015-08-20 18:27:24]

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

[commit-bot: I haz the power, 2015-08-20 18:28:01]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295053002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295053002/20001

[commit-bot: I haz the power, 2015-08-20 20:32:20]

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

[commit-bot: I haz the power, 2015-08-20 20:32:20]

Dry run: This issue passed the CQ dry run.

[esprehn, 2015-08-20 21:00:34]

The CQ bit was checked by esprehn@chromium.org

[commit-bot: I haz the power, 2015-08-20 21:01:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295053002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295053002/20001

[commit-bot: I haz the power, 2015-08-20 21:09:11]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200934