Make field trials activated in the GPU process be reflected in browser.

chrome/common/variations/child_process_field_trial_syncer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/variations/child_process_field_trial_syncer.h"
 
 #include <set>
 #include <utility>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
-#include "chrome/common/render_messages.h"
 #include "components/variations/variations_util.h"
 
 namespace chrome_variations {
 
 ChildProcessFieldTrialSyncer::ChildProcessFieldTrialSyncer(
-    IPC::Sender* ipc_sender) : ipc_sender_(ipc_sender) {}
+    base::FieldTrialList::Observer* observer)
+    : observer_(observer) {}
 
 ChildProcessFieldTrialSyncer::~ChildProcessFieldTrialSyncer() {}
 
 void ChildProcessFieldTrialSyncer::InitFieldTrialObserving(
     const base::CommandLine& command_line) {
   // Set up initial set of crash dump data for field trials in this process.
   variations::SetVariationListCrashKeys();
 
   // Listen for field trial activations to report them to the browser.
-  base::FieldTrialList::AddObserver(this);
+  base::FieldTrialList::AddObserver(observer_);
 
   // Some field trials may have been activated before this point. Notify the
   // browser of these activations now. To detect these, take the set difference
   // of currently active trials with the initially active trials.
   base::FieldTrial::ActiveGroups initially_active_trials;
   base::FieldTrialList::GetActiveFieldTrialGroupsFromString(
       command_line.GetSwitchValueASCII(switches::kForceFieldTrials),
       &initially_active_trials);
   std::set<std::string> initially_active_trials_set;
   for (const auto& entry : initially_active_trials) {
     initially_active_trials_set.insert(std::move(entry.trial_name));
   }
 
   base::FieldTrial::ActiveGroups current_active_trials;
   base::FieldTrialList::GetActiveFieldTrialGroups(&current_active_trials);
   for (const auto& trial : current_active_trials) {
     if (!ContainsKey(initially_active_trials_set, trial.trial_name))
-      OnFieldTrialGroupFinalized(trial.trial_name, trial.group_name);
+      observer_->OnFieldTrialGroupFinalized(trial.trial_name, trial.group_name);
   }
 }
 
 void ChildProcessFieldTrialSyncer::OnSetFieldTrialGroup(
     const std::string& trial_name,
     const std::string& group_name) {
   base::FieldTrial* trial =
       base::FieldTrialList::CreateFieldTrial(trial_name, group_name);
   // Ensure the trial is marked as "used" by calling group() on it if it is
   // marked as activated.
   trial->group();
   variations::SetVariationListCrashKeys();
 }
 
-void ChildProcessFieldTrialSyncer::OnFieldTrialGroupFinalized(
-    const std::string& trial_name,
-    const std::string& group_name) {
-  ipc_sender_->Send(new ChromeViewHostMsg_FieldTrialActivated(trial_name));
-}
-
 }  // namespace chrome_variations