Store and retrieve features from shared memory

base/metrics/field_trial.cc

Index: base/metrics/field_trial.cc
diff --git a/base/metrics/field_trial.cc b/base/metrics/field_trial.cc
index ee1629c2e55c40bf343f1e5f9db48f598c95e36d..831239835fe23c729bb128d4135eb269948c7865 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -66,9 +66,9 @@ const size_t kFieldTrialAllocationSize = 128 << 10;  // 128 KiB
 #endif
 
 // We create one FieldTrialEntry per field trial in shared memory, via
-// AddToAllocatorWhileLocked. The FieldTrialEntry is followed by a base::Pickle
-// object that we unpickle and read from. Any changes to this structure requires
-// a bump in kFieldTrialType id defined above.
+// AddTrialToAllocatorWhileLocked. The FieldTrialEntry is followed by a
+// base::Pickle object that we unpickle and read from. Any changes to this
+// structure requires a bump in kFieldTrialType id defined above.
 struct FieldTrialEntry {
   // Expected size for 32/64-bit check.
   static constexpr size_t kExpectedInstanceSize = 8;
@@ -739,6 +739,11 @@ void FieldTrialList::CreateTrialsFromCommandLine(
         std::set<std::string>());
     DCHECK(result);
   }
+
+  // TODO(lawrencewu): rename CreateTrialsFromCommandLine to
+  // CreateTrialsAndFeaturesFromCommandLine, cause that's what we're doing.
+  FeatureList::GetInstance()->InitializeFromSharedMemory(
+      global_->field_trial_allocator_.get());
 }
 
 #if defined(POSIX_WITH_ZYGOTE)
@@ -879,10 +884,10 @@ void FieldTrialList::OnGroupFinalized(bool is_locked, FieldTrial* field_trial) {
   if (!global_)
     return;
   if (is_locked) {
-    AddToAllocatorWhileLocked(field_trial);
+    AddTrialToAllocatorWhileLocked(field_trial);
   } else {
     AutoLock auto_lock(global_->lock_);
-    AddToAllocatorWhileLocked(field_trial);
+    AddTrialToAllocatorWhileLocked(field_trial);
   }
 }
 
@@ -1004,9 +1009,13 @@ void FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded() {
 
   // Add all existing field trials.
   for (const auto& registered : global_->registered_) {
-    AddToAllocatorWhileLocked(registered.second);
+    AddTrialToAllocatorWhileLocked(registered.second);
   }
 
+  // Add all existing features.
+  FeatureList::GetInstance()->AddFeaturesToAllocator(
+      global_->field_trial_allocator_.get());
+
 #if defined(OS_WIN) || defined(POSIX_WITH_ZYGOTE)
   // Set |readonly_allocator_handle_| so we can pass it to be inherited and
   // via the command line.
@@ -1017,7 +1026,7 @@ void FieldTrialList::InstantiateFieldTrialAllocatorIfNeeded() {
 #endif
 
 // static
-void FieldTrialList::AddToAllocatorWhileLocked(FieldTrial* field_trial) {
+void FieldTrialList::AddTrialToAllocatorWhileLocked(FieldTrial* field_trial) {
   FieldTrialAllocator* allocator = global_->field_trial_allocator_.get();
 
   // Don't do anything if the allocator hasn't been instantiated yet.
@@ -1075,7 +1084,7 @@ void FieldTrialList::ActivateFieldTrialEntryWhileLocked(
   if (ref == FieldTrialAllocator::kReferenceNull) {
     // It's fine to do this even if the allocator hasn't been instantiated
     // yet -- it'll just return early.
-    AddToAllocatorWhileLocked(field_trial);
+    AddTrialToAllocatorWhileLocked(field_trial);
   } else {
     // It's also okay to do this even though the callee doesn't have a lock --
     // the only thing that happens on a stale read here is a slight performance