4 files changed, 55 insertions, 4 deletions

diff --git a/base/field_trial.cc b/base/field_trial.cc
index 2b354d7..0bf39e2 100644
--- a/base/field_trial.cc
+++ b/base/field_trial.cc
@@ -67,9 +67,12 @@ std::string FieldTrial::MakeName(const std::string& name_prefix,
 // static
 FieldTrialList* FieldTrialList::global_ = NULL;
 
-FieldTrialList::FieldTrialList()
-  : application_start_time_(Time::Now()) {
+// static
+bool FieldTrialList::register_without_global_ = false;
+
+FieldTrialList::FieldTrialList() : application_start_time_(Time::Now()) {
   DCHECK(!global_);
+  DCHECK(!register_without_global_);
   global_ = this;
 }
 
@@ -86,9 +89,10 @@ FieldTrialList::~FieldTrialList() {
 
 // static
 void FieldTrialList::Register(FieldTrial* trial) {
-  DCHECK(global_);
-  if (!global_)
+  if (!global_) {
+    register_without_global_ = true;
     return;
+  }
   AutoLock auto_lock(global_->lock_);
   DCHECK(!global_->PreLockedFind(trial->name()));
   trial->AddRef();
diff --git a/base/field_trial.h b/base/field_trial.h
index fba0b01..a26bde8f 100644
--- a/base/field_trial.h
+++ b/base/field_trial.h
@@ -210,6 +210,11 @@ class FieldTrialList {
 
   static FieldTrialList* global_;  // The singleton of this class.
 
+  // This will tell us if there is an attempt to register a field trial without
+  // creating the FieldTrialList. This is not an error, unless a FieldTrialList
+  // is created after that.
+  static bool register_without_global_;
+
   // A helper value made availabel to users, that shows when the FieldTrialList
   // was initialized.  Note that this is a singleton instance, and hence is a
   // good approximation to the start of the process.
diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index f08ad79e..5000ec1 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -2947,6 +2947,22 @@ void RenderView::DumpLoadHistograms() const {
           kBeginToFinishMax, kBeginToFinishBucketCount);
   }
 
+  static bool use_cache_histogram1(FieldTrialList::Find("CacheSize") &&
+      !FieldTrialList::Find("CacheSize")->group_name().empty());
+  if (use_cache_histogram1)
+    UMA_HISTOGRAM_CUSTOM_TIMES(
+        FieldTrial::MakeName("Renderer4.StartToFinish", "CacheSize").data(),
+        finish - start, kBeginToFinishMin,
+        kBeginToFinishMax, kBeginToFinishBucketCount);
+
+  static bool use_cache_histogram2(FieldTrialList::Find("NewEviction") &&
+      !FieldTrialList::Find("NewEviction")->group_name().empty());
+  if (use_cache_histogram2)
+    UMA_HISTOGRAM_CUSTOM_TIMES(
+        FieldTrial::MakeName("Renderer4.StartToFinish", "NewEviction").data(),
+        finish - start, kBeginToFinishMin,
+        kBeginToFinishMax, kBeginToFinishBucketCount);
+
   UMA_HISTOGRAM_MEDIUM_TIMES("Renderer4.CommitToFinish", finish - commit);
 
   if (!first_paint.is_null()) {
diff --git a/net/disk_cache/backend_impl.cc b/net/disk_cache/backend_impl.cc
index e089660..ecbbcc2 100644
--- a/net/disk_cache/backend_impl.cc
+++ b/net/disk_cache/backend_impl.cc
@@ -4,6 +4,7 @@
 
 #include "net/disk_cache/backend_impl.h"
 
+#include "base/field_trial.h"
 #include "base/file_path.h"
 #include "base/file_util.h"
 #include "base/histogram.h"
@@ -169,6 +170,27 @@ bool InitExperiment(int* current_group) {
   return true;
 }
 
+// Initializes the field trial structures to allow performance measurements
+// for the current cache configuration.
+void SetFieldTrialInfo(int experiment_group, int size_group) {
+  static bool first = true;
+  if (!first)
+    return;
+
+  // Field trials involve static objects so we have to do this only once.
+  first = false;
+  scoped_refptr<FieldTrial> trial1 = new FieldTrial("CacheSize", 10);
+  std::string group1 = StringPrintf("CacheSizeGroup_%d", size_group);
+  trial1->AppendGroup(group1, FieldTrial::kAllRemainingProbability);
+
+  if (experiment_group < 6 || experiment_group > 8)
+    return;
+
+  scoped_refptr<FieldTrial> trial2 = new FieldTrial("NewEviction", 10);
+  std::string group2 = StringPrintf("NewEvictionGroup_%d", experiment_group);
+  trial2->AppendGroup(group2, FieldTrial::kAllRemainingProbability);
+}
+
 }  // namespace
 
 // ------------------------------------------------------------------------
@@ -303,6 +325,10 @@ bool BackendImpl::Init() {
   disabled_ = !rankings_.Init(this, new_eviction_);
   eviction_.Init(this);
 
+  // Setup experiment data only for the main cache.
+  if (cache_type() == net::DISK_CACHE)
+    SetFieldTrialInfo(data_->header.experiment, GetSizeGroup());
+
   return !disabled_;
 }