Disk cache: Close the current experiment for new users.

Intended for the Beta branch.
(this is a reland of 88690)

BUG=91040
TEST=none
TBR=gavinp@chromium.org
Review URL: http://codereview.chromium.org/7518006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@94764 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 6 insertions, 28 deletions

diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index b03ecda..900ea08 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -172,35 +172,13 @@ bool InitExperiment(disk_cache::IndexHeader* header, uint32 mask) {
     return false;
   }
 
-  // See if we already defined the group for this profile.
-  if (header->experiment > disk_cache::EXPERIMENT_DELETED_LIST_OUT) {
-    SetFieldTrialInfo(header->experiment);
-    return true;
-  }
-
-  if (!header->create_time || !header->lru.filled)
-    return true; // Wait untill we fill up the cache.
-
-  int index_load = header->num_entries * 100 / (mask + 1);
-  if (index_load > 25) {
-   // Out of the experiment (~18% users).
-   header->experiment = disk_cache::EXPERIMENT_DELETED_LIST_OUT2;
-   return true;
-  }
+  // The current experiment is closed for new profiles.
+  if (header->experiment < disk_cache::EXPERIMENT_DELETED_LIST_OUT)
+    header->experiment = disk_cache::EXPERIMENT_DELETED_LIST_OUT;
 
-  int option = base::RandInt(0, 4);
-  if (option > 1) {
-   // 60% out (49% of the total).
-   header->experiment = disk_cache::EXPERIMENT_DELETED_LIST_OUT2;
-  } else if (!option) {
-   // About 16% of the total.
-   header->experiment = disk_cache::EXPERIMENT_DELETED_LIST_CONTROL;
-  } else {
-   // About 16% of the total.
-   header->experiment = disk_cache::EXPERIMENT_DELETED_LIST_IN;
-  }
-
-  SetFieldTrialInfo(header->experiment);
+  // If we are part of the experiment, set up the field trial.
+  if (header->experiment > disk_cache::EXPERIMENT_DELETED_LIST_OUT)
+    SetFieldTrialInfo(header->experiment);
   return true;
 }