Prevent browser crashes when a site is added to shelf with extensions blacklisted.

Prevent browser crashes when a site is added to shelf with extensions blacklisted.

The bookmark app installer underpinning the add to shelf functionality
assumes the validity of the extension pointer returned from the app
installation process with a DCHECK. However, CrxInstaller issues a
DONE notification with a null extension pointer attached when
installation fails, e.g. when extensions are blacklisted. Dereferencing
the null pointer leads to a whole browser crash that is 100%
reproducible whenever add to shelf is used while extensions are
blacklisted (and under any other conditions which cause extension
installation to fail).

This CL fixes the crash by explicitly checking the extension pointer
instead of DCHECKing it. When a null extension pointer is returned from
CrxInstaller, add to shelf will silently fail and the browser won't
crash. A future CL will stop the add to shelf functionality from being
exposed if extensions are disabled by policy.

BUG=545541
Committed: https://crrev.com/a5a950ab63b1e7abb7dbdb03a50fb090144cc262
Cr-Commit-Position: refs/heads/master@{#356231}

[dominickn, 2015-10-27 02:35:42]

Description was changed from

==========
Prevent browser crashes when a site is added to shelf with extensions
blacklisted.

The bookmark app installer underpinning the add to shelf functionality
assumes the validity of the extension pointer returned from the
app installation process with a DCHECK. However, CrxInstaller returns a
null extension pointer when installation fails, e.g. when extensions are
blacklisted. Dereferencing the null pointer leads to a whole browser
crash that is 100% reproducible whenever add to shelf is used while
extensions are blacklisted (and under any other conditions which cause
extension installation to fail).

This CL fixes the crash by explicitly checking the extension pointer
instead of DCHECKing it. When a null extension pointer is returned from
CrxInstaller, add to shelf will silently fail and the browser won't
crash. A future CL will stop the add to shelf functionality from being
exposed if extensions are disabled by policy.

BUG=545541
==========

to

==========
Prevent browser crashes when a site is added to shelf with extensions
blacklisted.

The bookmark app installer underpinning the add to shelf functionality
assumes the validity of the extension pointer returned from the
app installation process with a DCHECK. However, CrxInstaller issues a
DONE notification with a null extension pointer attached when installation
fails, e.g. when extensions are blacklisted. Dereferencing the null pointer
leads to a whole browser crash that is 100% reproducible whenever add
to shelf is used while extensions are blacklisted (and under any other
conditions which cause extension installation to fail).

This CL fixes the crash by explicitly checking the extension pointer
instead of DCHECKing it. When a null extension pointer is returned from
CrxInstaller, add to shelf will silently fail and the browser won't
crash. A future CL will stop the add to shelf functionality from being
exposed if extensions are disabled by policy.

BUG=545541
==========

[dominickn, 2015-10-27 02:35:42]

dominickn@chromium.org changed reviewers:
+ benwells@chromium.org

[dominickn, 2015-10-27 02:36:16]

PTAL, thanks. Will be requesting merge to M46 and M47.

[dominickn, 2015-10-27 02:37:30]

Description was changed from

==========
Prevent browser crashes when a site is added to shelf with extensions
blacklisted.

The bookmark app installer underpinning the add to shelf functionality
assumes the validity of the extension pointer returned from the
app installation process with a DCHECK. However, CrxInstaller issues a
DONE notification with a null extension pointer attached when installation
fails, e.g. when extensions are blacklisted. Dereferencing the null pointer
leads to a whole browser crash that is 100% reproducible whenever add
to shelf is used while extensions are blacklisted (and under any other
conditions which cause extension installation to fail).

This CL fixes the crash by explicitly checking the extension pointer
instead of DCHECKing it. When a null extension pointer is returned from
CrxInstaller, add to shelf will silently fail and the browser won't
crash. A future CL will stop the add to shelf functionality from being
exposed if extensions are disabled by policy.

BUG=545541
==========

to

==========
Prevent browser crashes when a site is added to shelf with extensions
blacklisted.

The bookmark app installer underpinning the add to shelf functionality
assumes the validity of the extension pointer returned from the app
installation process with a DCHECK. However, CrxInstaller issues a
DONE notification with a null extension pointer attached when
installation fails, e.g. when extensions are blacklisted. Dereferencing
the null pointer leads to a whole browser crash that is 100%
reproducible whenever add to shelf is used while extensions are
blacklisted (and under any other conditions which cause extension
installation to fail).

This CL fixes the crash by explicitly checking the extension pointer
instead of DCHECKing it. When a null extension pointer is returned from
CrxInstaller, add to shelf will silently fail and the browser won't
crash. A future CL will stop the add to shelf functionality from being
exposed if extensions are disabled by policy.

BUG=545541
==========

[benwells, 2015-10-27 03:09:17]

lgtm

[dominickn, 2015-10-27 03:11:54]

The CQ bit was checked by dominickn@chromium.org

[commit-bot: I haz the power, 2015-10-27 03:12:03]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1424663005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1424663005/1

[commit-bot: I haz the power, 2015-10-27 03:21:10]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-27 03:22:06]

Patchset 1 (id:??) landed as
https://crrev.com/a5a950ab63b1e7abb7dbdb03a50fb090144cc262
Cr-Commit-Position: refs/heads/master@{#356231}