Fix duplicate insertions of default search providers into the Web Data database.

Fix duplicate insertions of default search providers into the Web Data database.

BUG=83203
TEST=Steps to reproduce the bug, or web_data_unittests.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=86277

[Joao da Silva, 2011-05-19 15:22:30]

Hi Jean-Luc, can you review this? Git says you wrote the original code :-)

The issue is that RemoveProvidersCreatedByPolicy removes all the search
providers that were added by policy from the vector _in memory_; the database
still keeps the entries. The subsequent code fails as per this example:

0. set the DefaultSearchProviderSearchURL policy to some value.
1. start Chrome with an empty profile
2. type something in the omnibar. This will trigger the load of the providers.
3. since the profile is empty, the builtin providers are automatically added:
Google (2), Yahoo (3) and Bing (4). The numbers are the id in the database.
4. then the provider from the managed preference is added with id 5.
5. close Chrome. Start it again. Type something to trigger the load.

6. now RemoveProvidersCreatedByPolicy will get the 4 providers, and remove the
last one, because it was added by policy.
7. the remaining providers are passed to SetTemplateURLs, which will step
next_id_ as the max of the ids found. This is 4, since the provider from policy
has been removed from the vector.
8. since the policy is still set, the provider will be persisted again. But it
wasn't removed from the database! It had id 5, and now next_id_ is 4, and an
INSERT will try to insert 5 again, leading to a crash.

This CL solves the problem by:
- also removing (old) providers set by policy from the database, not just from
the vector in memory;
- keeping the current default provider in the database even if it was set by
policy, IF it is also currently set by a managed preference (this is a small
optimization, to avoid removing and reinserting it all the time; that would also
keep bumping next_id_).

Let me know what you think.
Thanks!

[jeanluc1, 2011-05-19 21:08:39]

LGTM