[headless] Remove default browser context.

headless/lib/browser/headless_content_browser_client.cc

 // Copyright 2015 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 "headless/lib/browser/headless_content_browser_client.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 12 matching lines @@
 content::BrowserMainParts* HeadlessContentBrowserClient::CreateBrowserMainParts(
     const content::MainFunctionParams&) {
   std::unique_ptr<HeadlessBrowserMainParts> browser_main_parts =
       base::WrapUnique(new HeadlessBrowserMainParts(browser_));
   browser_->set_browser_main_parts(browser_main_parts.get());
   return browser_main_parts.release();
 }
 
 content::DevToolsManagerDelegate*
 HeadlessContentBrowserClient::GetDevToolsManagerDelegate() {
-  return new HeadlessDevToolsManagerDelegate(browser_);
+  std::unique_ptr<HeadlessDevToolsManagerDelegate> devtools_manager_delegate =

[Eric Seckler, 2016/08/03 12:17:57]

do we need a unique_ptr here? (I find it a little confusing to see a unique_ptr
in combination with weak pointers.) maybe a simple raw pointer is more suitable?

[altimin, 2016/08/03 12:46:18]

We're using unique_ptr to show that we're explicitly pass ownership to caller
(TBH, GetDevToolsManagerDelegate should have returned a unique_ptr instead of
raw pointer because it takes ownership. I hope that it will be fixed when
someone has some free time).

And what is the problem with using weak pointers with unique pointer? We do not
own this object, but we want to reference it if is alive. 

[Eric Seckler, 2016/08/03 13:55:30]

Hm, I guess this was a misguided feeling influenced by std::weak_ptr and not
actually applicable here :) Thanks!

+      base::WrapUnique(new HeadlessDevToolsManagerDelegate(browser_));
+  browser_->set_devtools_manager_delegate(
+      devtools_manager_delegate->GetWeakPtr());
+  return devtools_manager_delegate.release();
 }
 
 }  // namespace headless