Write last_modified date to Content Settings in the PrefProvider

components/content_settings/core/browser/content_settings_default_provider.cc

Index: components/content_settings/core/browser/content_settings_default_provider.cc
diff --git a/components/content_settings/core/browser/content_settings_default_provider.cc b/components/content_settings/core/browser/content_settings_default_provider.cc
index 261fedb9d6b65b28e16ce301e1dbab667e735104..9f1eea3763dd54c79548b1ef1da9b1f3f2855a54 100644
--- a/components/content_settings/core/browser/content_settings_default_provider.cc
+++ b/components/content_settings/core/browser/content_settings_default_provider.cc
@@ -70,7 +70,7 @@ class DefaultRuleIterator : public RuleIterator {
   Rule Next() override {
     DCHECK(HasNext());
     return Rule(ContentSettingsPattern::Wildcard(),
-                ContentSettingsPattern::Wildcard(),
+                ContentSettingsPattern::Wildcard(), base::Time(),

[msramek, 2017/04/19 10:49:16]

I would argue that we *do* want to use real timestamps here.

Deleting content settings for a time period should also reset the default
settings changed in that period. It would be complicated to reset them to the
previous state (because that would require us to keep a full history of their
state), but we could at least reset them to default.

WDYT?

[dullweber, 2017/04/19 15:02:45]

We currently don't delete the default setting and I think I would prefer to keep
it this way.
(https://cs.chromium.org/chromium/src/chrome/browser/browsing_data/chrome_brow...)

My interpretation is that the default permission is something that belongs to
the normal profile settings which are normally not deleted by CBD. Site specific
settings should be removable because they are usually set while browsing.

                 value_.release());
   }