Fixing flakiness of SaveDownloadableIFrame test.

Fixing flakiness of SaveDownloadableIFrame test.

The SaveDownloadableIFrame was flaky, because previously the call
to GetDownloadManager()->RemoveAllDownloads() could have happened
before the download of thisdayinhistory.xls has completed.  In this
case the (still in-progress) download item would not be removed (and
would confuse/fail the remainder of the test).

Fixing this by having the test wait for download completion.

BUG=537530
TEST=browser_tests.exe --gtest_filter=*SavePageBrowserTest*SaveDownloadableIFrame* --gtest_repeat=100

Committed: https://crrev.com/d17fd202e89a14c2e85eaaf0ed3f49ccf42d2a17
Cr-Commit-Position: refs/heads/master@{#354911}

[Łukasz Anforowicz, 2015-10-19 19:28:45]

lukasza@chromium.org changed reviewers:
+ rdsmith@chromium.org

[Łukasz Anforowicz, 2015-10-19 19:28:46]

Randy, could you please take a look?

[Randy Smith (Not in Mondays), 2015-10-19 19:33:33]

Give me a sketch of what was causing the flakiness?  (MIght be good to put in
the CL description as well.)  I presume the fix is in the !expected_path.empty()
test; what would lead to that being empty?

Also, just confirming that you've tested it manually with --gtest_repeat=N, for
some large N?

[Randy Smith (Not in Mondays), 2015-10-19 19:34:00]

On 2015/10/19 19:33:33, rdsmith wrote:
> Give me a sketch of what was causing the flakiness?  (MIght be good to put in
> the CL description as well.)  I presume the fix is in the
!expected_path.empty()
> test; what would lead to that being empty?

Whoops, somehow I thought that the description was minimal, when you already did
this.  Please ignore this request.

> 
> Also, just confirming that you've tested it manually with --gtest_repeat=N,
for
> some large N?

[Randy Smith (Not in Mondays), 2015-10-19 19:34:25]

LGTM modulo having done manual test.

[Łukasz Anforowicz, 2015-10-19 23:02:19]

The CQ bit was checked by lukasza@chromium.org

[Łukasz Anforowicz, 2015-10-19 23:02:19]

The patchset sent to the CQ was uploaded after l-g-t-m from rdsmith@chromium.org
Link to the patchset: https://codereview.chromium.org/1408393004/#ps20001
(title: "Rebasing...")

[commit-bot: I haz the power, 2015-10-19 23:04:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1408393004/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1408393004/20001

[commit-bot: I haz the power, 2015-10-19 23:34:59]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-19 23:36:21]

Patchset 2 (id:??) landed as
https://crrev.com/d17fd202e89a14c2e85eaaf0ed3f49ccf42d2a17
Cr-Commit-Position: refs/heads/master@{#354911}