Fixed some crashes when playing media from the blob URL.

Fixed some crashes when playing media from the blob URL.

The first problem that causes DCHECK failure is the access to Profile
from the IO thread. We should pass IO-thread-safe ResourceContext
instead of passing UI-thread confined BrowserContext (i.e. Profile).

We also must handle cases when blob URL resolves to NULL handle. There
are plenty of cases when this is true: the URL may be invalid or already
revoked, blob decoding may fail and so on.

BUG=429432
Committed: https://crrev.com/61cb84971f5f21eb83b7e3b3ac43364aafb9b2d4
Cr-Commit-Position: refs/heads/master@{#302775}

[mlopatkin, 2014-11-01 16:29:18]

mlopatkin@yandex-team.ru changed reviewers:
+ qinmin@chromium.org

[mlopatkin, 2014-11-01 16:35:18]

Hello,
please take a look, this patch aims to fix some crashes when trying to play
video from an invalid blob URL on the Android.

[qinmin, 2014-11-03 19:45:47]

lgtm

[mlopatkin, 2014-11-05 09:44:44]

The CQ bit was checked by mlopatkin@yandex-team.ru

[commit-bot: I haz the power, 2014-11-05 09:45:12]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/693263003/1

[commit-bot: I haz the power, 2014-11-05 10:29:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-05 10:30:38]

Patchset 1 (id:??) landed as
https://crrev.com/61cb84971f5f21eb83b7e3b3ac43364aafb9b2d4
Cr-Commit-Position: refs/heads/master@{#302775}