Use WaitForResizeComplete() instead of waiting for first paint.

Use WaitForResizeComplete() instead of waiting for first paint.

That should fix flakyness for the test on Windows with cl 134623005.

BUG=None

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=287526

[mlamouri (slow - plz ping), 2014-08-04 17:31:13]

The point of this CL is to fix the flakyness of screen_orientation_browsertest
that is made obvious by https://codereview.chromium.org/134623005/. I thought
that listening to the first paint would be enough. It seems to be working fine
in Linux and ChromeOS but is a bit flaky on Windows. I tried this CL locally on
Windows, ChromeOS and Linux with https://codereview.chromium.org/134623005/
applied and I got a 100% success rate.

jam@, could you have a look? :) (I'm reverting the changes in
test_navigator_observer.* that I introduced for that test.)

[mlamouri (slow - plz ping), 2014-08-04 17:50:40]

Moving review to jochen@ because jam@ is OOO.

[enne (OOO), 2014-08-04 20:42:54]

This appears to fix the Windows issues that I've seen when I ran it through a
try job combined with https://codereview.chromium.org/134623005.

[jochen (gone - plz use gerrit), 2014-08-05 09:08:29]

lgtm

[mlamouri (slow - plz ping), 2014-08-05 09:18:22]

The CQ bit was checked by mlamouri@chromium.org

[commit-bot: I haz the power, 2014-08-05 09:19:51]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mlamouri@chromium.org/441713002/1

[commit-bot: I haz the power, 2014-08-05 10:43:43]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[commit-bot: I haz the power, 2014-08-05 11:27:23]

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

[commit-bot: I haz the power, 2014-08-05 11:27:24]

Try jobs failed on following builders:
  linux_chromium_chromeos_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[mlamouri (slow - plz ping), 2014-08-05 12:13:06]

The CQ bit was checked by mlamouri@chromium.org

[commit-bot: I haz the power, 2014-08-05 12:14:18]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/mlamouri@chromium.org/441713002/1

[commit-bot: I haz the power, 2014-08-05 13:09:11]

Change committed as 287526