Suppress a variant callstack of the net::ProxyScriptDecider uninitialized read

BUG=329339
TBR=ellyjones@chromium.org

Review URL: https://codereview.chromium.org/112343009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241685 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241685
[sync] Move migration test code out of ProfileSyncServiceHarness

This is another in a series of CLs to clean up
ProfileSyncServiceHarness. It does a couple of things:

1) Moves all migration test code out of profile_sync_service_harness.{h|cc}
   and into migration_errors_test.cc.
2) Simplifies the code that checks for the completion of migration by
   adding a new subclass of StatusChangeChecker called MigrationChecker,
   which implements the MigrationObserver interface and keeps track of
   migration of all data types in a given profile.

BUG=323380
TEST=sync_integration_tests:Migration*
R=rlarocque@chromium.org

Review URL: https://codereview.chromium.org/105333003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241686 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241686