ChannelMojo: Add ChannelMojo::CanBeUsed() to enable it incrementally

content/renderer/render_thread_impl.cc

 // Copyright (c) 2012 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 "content/renderer/render_thread_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <map>
 #include <vector>
@@ skipping 296 matching lines @@
  private:
   int32_t routing_id_highmark_;
 };
 
 void CreateRenderFrameSetup(mojo::InterfaceRequest<RenderFrameSetup> request) {
   mojo::BindToRequest(new RenderFrameSetupImpl(), &request);
 }
 
 bool ShouldUseMojoChannel() {
   return CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableRendererMojoChannel);
+             switches::kEnableRendererMojoChannel) ||
+         ChannelMojo::CanBeUsed();
 }
 
 blink::WebGraphicsContext3D::Attributes GetOffscreenAttribs() {
   blink::WebGraphicsContext3D::Attributes attributes;
   attributes.shareResources = true;
   attributes.depth = false;
   attributes.stencil = false;
   attributes.antialias = false;
   attributes.noAutomaticFlushes = true;
   return attributes;
@@ skipping 1252 matching lines @@
   hidden_widget_count_--;
 
   if (!GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
     return;
   }
 
   ScheduleIdleHandler(kLongIdleHandlerDelayMs);
 }
 
 }  // namespace content