Move content:: scheme registrations from chrome/ to content/.

Move content:: scheme registrations from chrome/ to content/.

Both 'chrome:' and 'chrome-devtools:' are content-level schemes; we
should do their various renderer-side scheme registrations in content
(RenderThreadImpl::RegisterSchemes) rather than in chrome
(ChromeContentRendererClient::RenderThreadStarted).

R=jochen@chromium.org

Committed: https://crrev.com/dcd7aad11d33ffd6dffe440ce32a0228c0843a67
Cr-Commit-Position: refs/heads/master@{#330506}

[Mike West, 2015-05-19 08:03:39]

mkwst@chromium.org changed reviewers:
+ philipj@opera.com, sofbjornf@opera.com

[Mike West, 2015-05-19 08:03:40]

As briefly discussed in https://codereview.chromium.org/809153004/, these scheme
registrations would be better done in content than chrome. WDYT, Jochen?

sof, philipj: FYI, as this might have impact on embedders like Opera. Perhaps
you can verify locally that this would be an improvement for your codebase?

[jochen (gone - plz use gerrit), 2015-05-19 11:24:24]

lgtm

[Mike West, 2015-05-19 11:49:30]

The CQ bit was checked by mkwst@chromium.org

[commit-bot: I haz the power, 2015-05-19 11:49:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1137103003/1

[philipj_slow, 2015-05-19 11:53:41]

Thanks for keeping us in the loop. In general, the more that lives in content
the better it is for us, as we use the content layer. It's still possible that
this will cause trouble, but I have no particular reason to think so.

[commit-bot: I haz the power, 2015-05-19 11:53:57]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-19 11:54:50]

Patchset 1 (id:??) landed as
https://crrev.com/dcd7aad11d33ffd6dffe440ce32a0228c0843a67
Cr-Commit-Position: refs/heads/master@{#330506}

[hiroshige, 2015-05-19 13:06:37]

This CL caused Layout Test failures: https://crbug.com/489672.

This is because
WebSecurityPolicy::registerURLSchemeAsCORSEnabled(chrome_scheme);
is called in content_shell.
(it wasn't called in content_shell because it was in chrome, but is called now
because it is now in content).

[hiroshige, 2015-05-19 13:22:33]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1142213002/ by hiroshige@chromium.org.

The reason for reverting is: Breaks some layout tests

BUG=489672.