Update https engagement browsertest to always use HTML resources.

Update https engagement browsertest to always use HTML resources.

A few https engagement tests used the test server resource at URL '/'.
It turns out that this resource gets served with mime type text/plain,
which we're planning to have page load metrics infrastructure ignore
in the future. This change switches those tests to use '/simple.html'
which is served with mime type text/html.

Additionally, this change adds a new test
Navigate_Both_NonHtmlMainResource, which we'll use to verify that we do
not track non-HTML resources.  The test currently asserts that we do
track these resources, with a comment explaining that we'll update it
to assert they are untracked as part of fixing bug 627536.

BUG=627536
Committed: https://crrev.com/9ecb585652429b88c8a802833bfe24c7fef128d8
Cr-Commit-Position: refs/heads/master@{#405226}

[Bryan McQuade, 2016-07-12 19:57:34]

bmcquade@chromium.org changed reviewers:
+ felt@chromium.org

[Bryan McQuade, 2016-07-12 19:57:34]

PTAL

[felt, 2016-07-13 16:53:33]

lgtm, thanks bryan

[Bryan McQuade, 2016-07-13 18:23:46]

The CQ bit was checked by bmcquade@chromium.org

[commit-bot: I haz the power, 2016-07-13 18:24:40]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-13 19:40:59]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-07-13 19:41:53]

CQ bit was unchecked.

[commit-bot: I haz the power, 2016-07-13 19:44:29]

Description was changed from

==========
Update https engagement browsertest to always use HTML resources.

A few https engagement tests used the test server resource at URL '/'.
It turns out that this resource gets served with mime type text/plain,
which we're planning to have page load metrics infrastructure ignore
in the future. This change switches those tests to use '/simple.html'
which is served with mime type text/html.

Additionally, this change adds a new test
Navigate_Both_NonHtmlMainResource, which we'll use to verify that we do
not track non-HTML resources.  The test currently asserts that we do
track these resources, with a comment explaining that we'll update it
to assert they are untracked as part of fixing bug 627536.

BUG=627536
==========

to

==========
Update https engagement browsertest to always use HTML resources.

A few https engagement tests used the test server resource at URL '/'.
It turns out that this resource gets served with mime type text/plain,
which we're planning to have page load metrics infrastructure ignore
in the future. This change switches those tests to use '/simple.html'
which is served with mime type text/html.

Additionally, this change adds a new test
Navigate_Both_NonHtmlMainResource, which we'll use to verify that we do
not track non-HTML resources.  The test currently asserts that we do
track these resources, with a comment explaining that we'll update it
to assert they are untracked as part of fixing bug 627536.

BUG=627536

Committed: https://crrev.com/9ecb585652429b88c8a802833bfe24c7fef128d8
Cr-Commit-Position: refs/heads/master@{#405226}
==========

[commit-bot: I haz the power, 2016-07-13 19:44:30]

Patchset 1 (id:??) landed as
https://crrev.com/9ecb585652429b88c8a802833bfe24c7fef128d8
Cr-Commit-Position: refs/heads/master@{#405226}