(Reland) Service Worker: Handle same-scope, new script registration

(Reland) Service Worker: Handle same-scope, new script registration

Reland of 2da192aff after:
- disabling some layout tests that need to be rebaselined
- landing 6cce6b78f "Decouple script_url from ServiceWorkerRegistration"
so Registration doesn't get in a weird state with a script_url that failed to
register

Before this patch, register() would delete an existing registration at
the scope if the script URL didn't match, and register a new one. This
overwriting creates a scenario where old tabs have a different
controller than new tabs, which the Service Worker spec avoids.

This patch implements the spec steps for same-scope, new script
register(). That means:
- If the existing registration is uninstalling, wait for that to
complete before doing anything.
- Create a new worker which becomes the installing worker of the
existing registration.

BUG=398355
TEST=https://codereview.chromium.org/480943002/

Committed: https://crrev.com/0b0c1c512f7a797a3f5ba679507109af87d12e1b
Cr-Commit-Position: refs/heads/master@{#292106}

[falken, 2014-08-26 15:46:26]

falken@chromium.org changed reviewers:
+ michaeln@chromium.org, nhiroki@chromium.org

[falken, 2014-08-26 15:46:26]

michaeln, nhiroki: PTAL.

This is the same patch as https://codereview.chromium.org/472103003/

The differences are:
- I'll disable some Blink layout tests before landing, and rebaseline in
https://codereview.chromium.org/480943002/
- I landed https://codereview.chromium.org/501453002/ in response to michaeln's
feedback on the earlier patch
- Some merging was needed to apply to ToT

[michaeln, 2014-08-27 00:30:24]

lgtm (i can pick up landing these patches if you like)

[falken, 2014-08-27 04:20:50]

Thanks! I'll try to power through :) The Blink test expectations landed so I'll
go ahead with the reland.

[falken, 2014-08-27 04:21:01]

The CQ bit was checked by falken@chromium.org

[commit-bot: I haz the power, 2014-08-27 04:22:02]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/falken@chromium.org/506043002/60001

[commit-bot: I haz the power, 2014-08-27 05:24:52]

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

[commit-bot: I haz the power, 2014-08-27 06:49:39]

Committed patchset #4 (60001) as 21199494fb1a8adbf60cce5ae375a582e4d3204d

[commit-bot: I haz the power, 2014-09-10 02:50:01]

Patchset 4 (id:??) landed as
https://crrev.com/0b0c1c512f7a797a3f5ba679507109af87d12e1b
Cr-Commit-Position: refs/heads/master@{#292106}