Introduce RenderFrame::IsMainFrame and clean up a few things.

chrome/renderer/chrome_content_renderer_client.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 "chrome/renderer/chrome_content_renderer_client.h"
 
 #include "base/command_line.h"
 #include "base/debug/crash_logging.h"
 #include "base/logging.h"
 #include "base/metrics/field_trial.h"
@@ skipping 532 matching lines @@
 #endif
 
 #if defined(ENABLE_PLUGINS)
   new PepperHelper(render_frame);
 #endif
 
 #if !defined(DISABLE_NACL)
   new nacl::NaClHelper(render_frame);
 #endif
 
-  // TODO(jam): when the frame tree moves into content and parent() works at
-  // RenderFrame construction, simplify this by just checking parent().
-  if (render_frame->GetRenderView()->GetMainRenderFrame() != render_frame) {
+  if (render_frame->IsMainFrame()) {
+    // Only attach NetErrorHelper to the main frame, since only the main frame
+    // should get error pages.
+    new NetErrorHelper(render_frame);
+
+    // Only attach MainRenderFrameObserver to the main frame, since
+    // we only want to log page load metrics for the main frame.
+    new page_load_metrics::MetricsRenderFrameObserver(render_frame);
+  } else {
     // Avoid any race conditions from having the browser tell subframes that
     // they're prerendering.
     if (prerender::PrerenderHelper::IsPrerendering(
             render_frame->GetRenderView()->GetMainRenderFrame())) {
       new prerender::PrerenderHelper(render_frame);
     }
   }
 
-  if (render_frame->GetRenderView()->GetMainRenderFrame() == render_frame) {
-    // Only attach NetErrorHelper to the main frame, since only the main frame
-    // should get error pages.
-    new NetErrorHelper(render_frame);
-  }
-
-  if (render_frame->GetWebFrame()->parent() == nullptr) {
-    // Only attach MainRenderFrameObserver to the main frame, since
-    // we only want to log page load metrics for the main frame.
-    new page_load_metrics::MetricsRenderFrameObserver(render_frame);
-  }
-
   // Set up a mojo service to test if this page is a distiller page.
   new dom_distiller::DistillerJsRenderFrameObserver(
       render_frame, chrome::ISOLATED_WORLD_ID_CHROME_INTERNAL);
 
   PasswordAutofillAgent* password_autofill_agent =
       new PasswordAutofillAgent(render_frame);
   PasswordGenerationAgent* password_generation_agent =
       new PasswordGenerationAgent(render_frame, password_autofill_agent);
   new AutofillAgent(render_frame, password_autofill_agent,
                     password_generation_agent);
@@ skipping 1083 matching lines @@
 }
 
 void ChromeContentRendererClient::WillDestroyServiceWorkerContextOnWorkerThread(
     v8::Local<v8::Context> context,
     const GURL& url) {
 #if defined(ENABLE_EXTENSIONS)
   extensions::Dispatcher::WillDestroyServiceWorkerContextOnWorkerThread(context,
                                                                         url);
 #endif
 }