Add support for the control group in the Simple Cache Experiment.

net/disk_cache/backend_impl.cc

Index: net/disk_cache/backend_impl.cc
diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index fed0546fc00daa6e96c29b24d293d4c0407b72b1..86d9ddbba66a0c202a47dfb13420438c21393592 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -76,13 +76,27 @@ size_t GetIndexSize(int table_len) {
 
 // Sets group for the current experiment. Returns false if the files should be
 // discarded.
-bool InitExperiment(disk_cache::IndexHeader* header) {
+bool InitExperiment(disk_cache::IndexHeader* header,
+                    bool cache_created) {
   if (header->experiment == disk_cache::EXPERIMENT_OLD_FILE1 ||
       header->experiment == disk_cache::EXPERIMENT_OLD_FILE2) {
     // Discard current cache.
     return false;
   }
 
+
+  LOG(INFO) << "hi?";

[rvargas (doing something else), 2013/04/19 17:40:55]

remove

+  if (base::FieldTrialList::FindFullName("SimpleCacheTrial") == "Control") {
+    if (cache_created) {
+      LOG(INFO) << "updating to control";

[rvargas (doing something else), 2013/04/19 17:40:55]

remove

+      header->experiment = disk_cache::EXPERIMENT_SIMPLE_CONTROL;
+      return true;
+    } else if (header->experiment != disk_cache::EXPERIMENT_SIMPLE_CONTROL) {
+      LOG(INFO) << "YR IN THE WRONG GROUP " << header->experiment;

[rvargas (doing something else), 2013/04/19 17:40:55]

remove

[gavinp, 2013/04/20 07:17:32]

Guh. Sorry for leaving these in.

Now you know how I debug.

+      return false;
+    }
+  }
+
   header->experiment = disk_cache::NO_EXPERIMENT;
   return true;
 }
@@ -258,9 +272,10 @@ int BackendImpl::SyncInit() {
   if (!restarted_ && (create_files || !data_->header.num_entries))
     ReportError(ERR_CACHE_CREATED);
 
-  if (!(user_flags_ & kNoRandom) &&
-      cache_type_ == net::DISK_CACHE && !InitExperiment(&data_->header))
+  if (!(user_flags_ & kNoRandom) && cache_type_ == net::DISK_CACHE &&
+      !InitExperiment(&data_->header, create_files)) {
     return net::ERR_FAILED;
+  }
 
   // We don't care if the value overflows. The only thing we care about is that
   // the id cannot be zero, because that value is used as "not dirty".