Remove profile-based per-host & default zoom level migration code.

Remove profile-based per-host & default zoom level migration code.

User migrations from the old-style zoom preferences has dropped below
a small fraction of a percent, so this CL removes the migration
machinery.

BUG=420643
Committed: https://crrev.com/5f5c5dd8f96e734631e49f2c78f75877cb170797
Cr-Commit-Position: refs/heads/master@{#343997}

[wjmaclean, 2015-08-18 17:40:17]

The CQ bit was checked by wjmaclean@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-18 17:40:50]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295323002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295323002/1

[wjmaclean, 2015-08-18 17:42:43]

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

[wjmaclean, 2015-08-18 17:42:43]

Relatively small/simple clean-up CL ... please take a look?

[Lei Zhang, 2015-08-18 18:38:41]

lgtm!

[commit-bot: I haz the power, 2015-08-18 18:50:52]

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

[commit-bot: I haz the power, 2015-08-18 18:50:52]

Dry run: Try jobs failed on following builders:
  linux_chromium_asan_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[wjmaclean, 2015-08-18 18:54:13]

The CQ bit was checked by wjmaclean@chromium.org

[commit-bot: I haz the power, 2015-08-18 18:54:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295323002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295323002/1

[commit-bot: I haz the power, 2015-08-18 19:30:28]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-08-18 19:31:14]

Patchset 1 (id:??) landed as
https://crrev.com/5f5c5dd8f96e734631e49f2c78f75877cb170797
Cr-Commit-Position: refs/heads/master@{#343997}

[gab, 2015-08-18 20:39:40]

gab@chromium.org changed reviewers:
+ gab@chromium.org

[gab, 2015-08-18 20:39:41]

Thanks, drive-by nits.

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
File chrome/browser/prefs/browser_prefs.cc (left):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
chrome/browser/prefs/browser_prefs.cc:585: 
https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/prefs/b...
had introduced some includes, can they be cleaned here?

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
chrome/browser/prefs/browser_prefs.cc:625:
UMA_HISTOGRAM_BOOLEAN("Settings.ZoomLevelPreferencesMigrated", migrated);
Also mark this histogram as obsolete.

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
File chrome/browser/profiles/host_zoom_map_browsertest.cc (left):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
chrome/browser/profiles/host_zoom_map_browsertest.cc:358: // In this case we
migrate the zoom level data from the profile prefs.
Includes cleanup from
https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/profile...
?

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/pro...
File chrome/browser/profiles/profile_impl.cc (right):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/pro...
chrome/browser/profiles/profile_impl.cc:73: #include
"chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
rm this include

[wjmaclean, 2015-08-19 13:53:34]

I've addressed your comments in a new issue:

https://codereview.chromium.org/1297503008/

Please see responses below.

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
File chrome/browser/prefs/browser_prefs.cc (left):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
chrome/browser/prefs/browser_prefs.cc:585: 
On 2015/08/18 20:39:40, gab wrote:
>
https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/prefs/b...
> had introduced some includes, can they be cleaned here?

Sorry, forgot about that.

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/prefs/browse...
chrome/browser/prefs/browser_prefs.cc:625:
UMA_HISTOGRAM_BOOLEAN("Settings.ZoomLevelPreferencesMigrated", migrated);
On 2015/08/18 20:39:40, gab wrote:
> Also mark this histogram as obsolete.

Done. I didn't realize that histograms had an 'obsolete' label ... good to know!

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
File chrome/browser/profiles/host_zoom_map_browsertest.cc (left):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
chrome/browser/profiles/host_zoom_map_browsertest.cc:358: // In this case we
migrate the zoom level data from the profile prefs.
On 2015/08/18 20:39:40, gab wrote:
> Includes cleanup from
>
https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/profile...
> ?

Did you want me to revert the changes to HostZoomMapBrowserTestWithPrefs as
well? I thought they might be useful as is, and certainly would be useful if we
write more prefs-tests. But I can remove them if you like.

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/pro...
File chrome/browser/profiles/profile_impl.cc (right):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/pro...
chrome/browser/profiles/profile_impl.cc:73: #include
"chrome/browser/ui/zoom/chrome_zoom_level_prefs.h"
On 2015/08/18 20:39:40, gab wrote:
> rm this include

Done.

[gab, 2015-08-20 16:34:29]

Thanks

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
File chrome/browser/profiles/host_zoom_map_browsertest.cc (left):

https://codereview.chromium.org/1295323002/diff/1/chrome/browser/profiles/hos...
chrome/browser/profiles/host_zoom_map_browsertest.cc:358: // In this case we
migrate the zoom level data from the profile prefs.
On 2015/08/19 13:53:34, wjmaclean wrote:
> On 2015/08/18 20:39:40, gab wrote:
> > Includes cleanup from
> >
>
https://codereview.chromium.org/541103002/diff/1040001/chrome/browser/profile...
> > ?
> 
> Did you want me to revert the changes to HostZoomMapBrowserTestWithPrefs as
> well? I thought they might be useful as is, and certainly would be useful if
we
> write more prefs-tests. But I can remove them if you like.

Don't feel strongly there, feels like most of the other changes still apply?
Feel free to remove any now overly generic path.