Remove fixed header at chrome://inspect

Remove fixed header at chrome://inspect

The fixed header gets in the way when the user zooms in and attempts to
scroll the page. To fix this issue, the header is no longer at a
viewport-fixed position, but at a static position within the main
content. The location specified by the page header is already displayed
in the left navigation bar, so this change does not hurt usability.

BUG=492124
Committed: https://crrev.com/0d96227ee3378a3b0676f7923560c69f0a8209c7
Cr-Commit-Position: refs/heads/master@{#334722}

[robwu, 2015-06-15 16:39:50]

rob@robwu.nl changed reviewers:
+ pfeldman@chromium.org

[robwu, 2015-06-15 16:39:50]

Yet another CL for chrome://inspect/...

To manually test the changes:
1. get Canary
2. Visit chrome://inspect
3. Inspect any .content-header and remove position:fixed.
4. Inspect the parent node and assign padding-top:0 to #content > div.
5. Zoom in and scroll the page (resize the window if the window is too big).

[pfeldman, 2015-06-16 18:40:37]

lgtm

[robwu, 2015-06-16 20:46:02]

The CQ bit was checked by rob@robwu.nl

[commit-bot: I haz the power, 2015-06-16 20:49:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1187813004/1

[commit-bot: I haz the power, 2015-06-16 22:40:45]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-16 22:42:22]

Patchset 1 (id:??) landed as
https://crrev.com/0d96227ee3378a3b0676f7923560c69f0a8209c7
Cr-Commit-Position: refs/heads/master@{#334722}