[DevTools] Enable "auto attach to sub frames" by default

chrome/browser/devtools/devtools_window.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/browser/devtools/devtools_window.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/command_line.h"
@@ skipping 629 matching lines @@
     window->ScheduleShow(action);
   else
     window->CloseWindow();
 }
 
 // static
 void DevToolsWindow::InspectElement(
     content::RenderFrameHost* inspected_frame_host,
     int x,
     int y) {
+  WebContents* web_contents =
+      WebContents::FromRenderFrameHost(inspected_frame_host);
   scoped_refptr<DevToolsAgentHost> agent(
-      DevToolsAgentHost::GetOrCreateFor(inspected_frame_host));
+      DevToolsAgentHost::GetOrCreateFor(web_contents));
   bool should_measure_time = FindDevToolsWindow(agent.get()) == NULL;
   base::TimeTicks start_time = base::TimeTicks::Now();
   // TODO(loislo): we should initiate DevTools window opening from within
   // renderer. Otherwise, we still can hit a race condition here.
-  if (agent->GetType() == content::DevToolsAgentHost::kTypePage) {
-    OpenDevToolsWindow(agent->GetWebContents(),
-                       DevToolsToggleAction::ShowElementsPanel());
-  } else {
-    OpenDevToolsWindowForFrame(Profile::FromBrowserContext(
-                                   agent->GetBrowserContext()), agent);
-  }
+  OpenDevToolsWindow(web_contents, DevToolsToggleAction::ShowElementsPanel());
   DevToolsWindow* window = FindDevToolsWindow(agent.get());
   if (window) {
     agent->InspectElement(window->bindings_, x, y);
     if (should_measure_time)
       window->inspect_element_start_time_ = start_time;
   }
 }
 
 void DevToolsWindow::ScheduleShow(const DevToolsToggleAction& action) {
   if (life_stage_ == kLoadCompleted) {
@@ skipping 760 matching lines @@
 bool DevToolsWindow::ReloadInspectedWebContents(bool bypass_cache) {
   // Only route reload via front-end if the agent is attached.
   WebContents* wc = GetInspectedWebContents();
   if (!wc || wc->GetCrashedStatus() != base::TERMINATION_STATUS_STILL_RUNNING)
     return false;
   base::Value bypass_cache_value(bypass_cache);
   bindings_->CallClientFunction("DevToolsAPI.reloadInspectedPage",
                                 &bypass_cache_value, nullptr, nullptr);
   return true;
 }