Fix crash in ChromeZoomLevelPrefs::ExtractPerHostZoomLevels().

Fix crash in ChromeZoomLevelPrefs::ExtractPerHostZoomLevels().

This CL fixes a crash that occurs when ExtractPerHostZoomLevels is
called with a legacy per-host zoom level dictionary. In this case the
sanitization code will fail to find a partition key and subsequently
dereference a null pointer.

Since the legacy dictionary will be deleted immediately after the
function exits, we just skip the sanitization in this case.

BUG=424540
Committed: https://crrev.com/d94fd1d623893516b98e59e2b79e512ac26556f4
Cr-Commit-Position: refs/heads/master@{#300501}

[wjmaclean, 2014-10-21 13:36:30]

wjmaclean@chromium.org changed reviewers:
+ bauerb@chromium.org

[wjmaclean, 2014-10-21 13:36:31]

bauerb@ - can you please take a look at this short CL?

[Bernhard Bauer, 2014-10-21 14:13:13]

LGTM with a suggestion:

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
File chrome/browser/ui/zoom/chrome_zoom_level_prefs.h (right):

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
chrome/browser/ui/zoom/chrome_zoom_level_prefs.h:57: const char*
dictionary_path);
An alternative would be to pass in a boolean that says whether to sanitize or
not. There are only two valid strings to pass in here anyway.

[wjmaclean, 2014-10-21 14:21:49]

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
File chrome/browser/ui/zoom/chrome_zoom_level_prefs.h (right):

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
chrome/browser/ui/zoom/chrome_zoom_level_prefs.h:57: const char*
dictionary_path);
On 2014/10/21 14:13:13, Bernhard Bauer wrote:
> An alternative would be to pass in a boolean that says whether to sanitize or
> not. There are only two valid strings to pass in here anyway.

I thought about using a bool, but then with the general feeling about enums
being preferred over bools for function parameters I thought this might be
simpler. In light of that, I'm still happy to switch to bools with comments at
the call site if you think that's ok (I'm not opposed to bools if we can use
comments).

[Bernhard Bauer, 2014-10-21 14:26:15]

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
File chrome/browser/ui/zoom/chrome_zoom_level_prefs.h (right):

https://codereview.chromium.org/665283002/diff/1/chrome/browser/ui/zoom/chrom...
chrome/browser/ui/zoom/chrome_zoom_level_prefs.h:57: const char*
dictionary_path);
On 2014/10/21 14:21:49, wjmaclean wrote:
> On 2014/10/21 14:13:13, Bernhard Bauer wrote:
> > An alternative would be to pass in a boolean that says whether to sanitize
or
> > not. There are only two valid strings to pass in here anyway.
> 
> I thought about using a bool, but then with the general feeling about enums
> being preferred over bools for function parameters I thought this might be
> simpler. In light of that, I'm still happy to switch to bools with comments at
> the call site if you think that's ok (I'm not opposed to bools if we can use
> comments).

Yeah, I'm absolutely okay with using well-commented bools.

[wjmaclean, 2014-10-21 15:11:19]

The CQ bit was checked by wjmaclean@chromium.org

[commit-bot: I haz the power, 2014-10-21 15:12:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/665283002/20001

[commit-bot: I haz the power, 2014-10-21 16:16:49]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-21 16:16:51]

Try jobs failed on following builders:
  linux_chromium_rel_swarming on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[wjmaclean, 2014-10-21 16:18:24]

The CQ bit was checked by wjmaclean@chromium.org

[commit-bot: I haz the power, 2014-10-21 16:19:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/665283002/20001

[commit-bot: I haz the power, 2014-10-21 16:47:34]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-10-21 16:48:39]

Patchset 2 (id:??) landed as
https://crrev.com/d94fd1d623893516b98e59e2b79e512ac26556f4
Cr-Commit-Position: refs/heads/master@{#300501}