[headless] Remove default browser context.

headless/lib/browser/headless_content_browser_client.cc

Index: headless/lib/browser/headless_content_browser_client.cc
diff --git a/headless/lib/browser/headless_content_browser_client.cc b/headless/lib/browser/headless_content_browser_client.cc
index 23ddee0d580d82b1e46cd70a0a8d56cc652c9916..4a52361a0efd4932d9f2a422e099c9060c1f26a9 100644
--- a/headless/lib/browser/headless_content_browser_client.cc
+++ b/headless/lib/browser/headless_content_browser_client.cc
@@ -30,7 +30,11 @@ content::BrowserMainParts* HeadlessContentBrowserClient::CreateBrowserMainParts(
 
 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