Store field trial parameters in 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 63f549e5729d69b3587de96dbef7ad61764bac26..388e1171e2e40e0d86e5c4d9fefd012c213fdbaf 100644
--- a/base/metrics/field_trial.cc
+++ b/base/metrics/field_trial.cc
@@ -12,6 +12,7 @@
 #include "base/command_line.h"
 #include "base/feature_list.h"
 #include "base/logging.h"
+#include "base/metrics/field_trial_param_associator.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/pickle.h"
 #include "base/process/memory.h"
@@ -55,21 +56,23 @@ struct FieldTrialEntry {
 
   // Size of the pickled structure, NOT the total size of this entry.
   uint32_t size;

[Alexei Svitkine (slow), 2016/11/01 14:57:16]

Add a blank line below this and a comment about the function.

[lawrencewu, 2016/11/01 18:29:05]

Done.

+  PickleIterator GetPickleIterator() const {
+    char* src = reinterpret_cast<char*>(const_cast<FieldTrialEntry*>(this)) +
+                sizeof(FieldTrialEntry);
+
+    Pickle pickle(src, size);
+    return PickleIterator(pickle);
+  }
 
   // Calling this is only valid when the entry is initialized. That is, it
   // resides in shared memory and has a pickle containing the trial name and
   // group name following it.
   bool GetTrialAndGroupName(StringPiece* trial_name,
                             StringPiece* group_name) const {
-    char* src = reinterpret_cast<char*>(const_cast<FieldTrialEntry*>(this)) +
-                sizeof(FieldTrialEntry);
-
-    Pickle pickle(src, size);
-    PickleIterator pickle_iter(pickle);
-
-    if (!pickle_iter.ReadStringPiece(trial_name))
+    PickleIterator iter = GetPickleIterator();
+    if (!iter.ReadStringPiece(trial_name))
       return false;
-    if (!pickle_iter.ReadStringPiece(group_name))
+    if (!iter.ReadStringPiece(group_name))
       return false;
     return true;
   }
@@ -181,6 +184,24 @@ HANDLE CreateReadOnlyHandle(SharedPersistentMemoryAllocator* allocator) {
 }
 #endif
 
+bool PickleFieldTrialState(const FieldTrial::State& trial_state,
+                           Pickle* pickle) {
+  pickle->WriteString(trial_state.trial_name);
+  pickle->WriteString(trial_state.group_name);
+
+  std::map<std::string, std::string> params;
+  if (!FieldTrialParamAssociator::GetInstance()->GetFieldTrialParamsWhileLocked(
+          trial_state.trial_name.as_string(),
+          trial_state.group_name.as_string(), &params))

[Alexei Svitkine (slow), 2016/11/01 14:57:16]

Nit: {}'s

[lawrencewu, 2016/11/01 18:29:05]

Done.

+    return false;
+
+  for (const auto& param : params) {
+    pickle->WriteString(StringPiece(param.first));
+    pickle->WriteString(StringPiece(param.second));

[Alexei Svitkine (slow), 2016/11/01 14:57:16]

Can you also add the changes to actually read from these to
FieldTrialParamAssociator?

I'd rather have both parts be in the same CL.

[lawrencewu, 2016/11/01 18:29:05]

Done.

+  }
+  return true;
+}
+
 }  // namespace
 
 // statics
@@ -904,8 +925,8 @@ void FieldTrialList::AddToAllocatorWhileLocked(FieldTrial* field_trial) {
     return;
 
   Pickle pickle;
-  pickle.WriteString(trial_state.trial_name);
-  pickle.WriteString(trial_state.group_name);
+  if (!PickleFieldTrialState(trial_state, &pickle))
+    return;
 
   size_t total_size = sizeof(FieldTrialEntry) + pickle.size();
   SharedPersistentMemoryAllocator::Reference ref =