Convert FieldTrialActivated to use mojo.

chrome/browser/renderer_host/chrome_render_message_filter.cc

Index: chrome/browser/renderer_host/chrome_render_message_filter.cc
diff --git a/chrome/browser/renderer_host/chrome_render_message_filter.cc b/chrome/browser/renderer_host/chrome_render_message_filter.cc
index 44b6ad01babc8cbad3bd2467f99b6236fb493160..e9d8c7fa930bc1464d7d6e8e1670b5d50dacc241 100644
--- a/chrome/browser/renderer_host/chrome_render_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_render_message_filter.cc
@@ -12,7 +12,6 @@
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/macros.h"
-#include "base/metrics/field_trial.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/content_settings/cookie_settings_factory.h"
@@ -85,8 +84,6 @@ bool ChromeRenderMessageFilter::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(ChromeViewHostMsg_IsCrashReportingEnabled,
                         OnIsCrashReportingEnabled)
 #endif
-    IPC_MESSAGE_HANDLER(ChromeViewHostMsg_FieldTrialActivated,
-                        OnFieldTrialActivated)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
 
@@ -349,11 +346,3 @@ void ChromeRenderMessageFilter::OnIsCrashReportingEnabled(bool* enabled) {
   *enabled = ChromeMetricsServiceAccessor::IsMetricsAndCrashReportingEnabled();
 }
 #endif
-
-void ChromeRenderMessageFilter::OnFieldTrialActivated(
-    const std::string& trial_name) {
-  // Activate the trial in the browser process to match its state in the
-  // renderer. This is done by calling FindFullName which finalizes the group
-  // and activates the trial.
-  base::FieldTrialList::FindFullName(trial_name);
-}