Use SharedPersistentMemoryAllocator to share field trial state

content/browser/renderer_host/render_process_host_impl.cc

Index: content/browser/renderer_host/render_process_host_impl.cc
diff --git a/content/browser/renderer_host/render_process_host_impl.cc b/content/browser/renderer_host/render_process_host_impl.cc
index 088b7196b9c210ff5c5e93333b1da9907e15ca4c..f3b000254520f47cac12ba211a00eb8862959def 100644
--- a/content/browser/renderer_host/render_process_host_impl.cc
+++ b/content/browser/renderer_host/render_process_host_impl.cc
@@ -909,7 +909,7 @@ bool RenderProcessHostImpl::Init() {
     // at this stage.
     child_process_launcher_.reset(new ChildProcessLauncher(
         new RendererSandboxedProcessLauncherDelegate(channel_.get()), cmd_line,
-        GetID(), this, field_trial_state_.get(), child_token_,
+        GetID(), this, child_token_,
         base::Bind(&RenderProcessHostImpl::OnMojoError, id_)));
     channel_->Pause();
 
@@ -1822,8 +1822,7 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
   renderer_cmd->CopySwitchesFrom(browser_cmd, kSwitchNames,
                                  arraysize(kSwitchNames));
 
-  field_trial_state_ =
-      BrowserChildProcessHostImpl::CopyFeatureAndFieldTrialFlags(renderer_cmd);
+  BrowserChildProcessHostImpl::CopyFeatureAndFieldTrialFlags(renderer_cmd);
 
   if (browser_cmd.HasSwitch(switches::kTraceStartup) &&
       BrowserMainLoop::GetInstance()->is_tracing_startup_for_duration()) {