Fix issues related to request and context object lifespan (issue #1037, issue #1044).

- Simplify and document the relationship between the various context object types. See browser_context.h for a description of the new relationships.
- cefclient: Add `request-context-per-browser` command-line flag for testing multiple CefRequestContext instances.
- cefclient: Add a CefURLRequest example.

git-svn-id: https://chromiumembedded.googlecode.com/svn/trunk@2032 5089003a-bbd8-11dd-ad1f-f1f9622dbc98

libcef/browser/resource_context.cc

@@ -0,0 +1,42 @@
+// Copyright (c) 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 "libcef/browser/resource_context.h"
+#include "libcef/browser/url_request_context_getter.h"
+
+#include "base/logging.h"
+#include "content/public/browser/browser_thread.h"
+
+CefResourceContext::CefResourceContext() {
+}
+
+CefResourceContext::~CefResourceContext() {
+  if (getter_.get()) {
+    // When the parent object (ResourceContext) destructor executes all
+    // associated URLRequests should be destroyed. If there are no other
+    // references it should then be safe to destroy the URLRequestContextGetter
+    // which owns the URLRequestContext.
+    getter_->AddRef();
+    CefURLRequestContextGetter* raw_getter = getter_.get();
+    getter_ = NULL;
+    content::BrowserThread::ReleaseSoon(
+          content::BrowserThread::IO, FROM_HERE, raw_getter);
+  }
+}
+
+net::HostResolver* CefResourceContext::GetHostResolver() {
+  CHECK(getter_.get());
+  return getter_->GetHostResolver();
+}
+
+net::URLRequestContext* CefResourceContext::GetRequestContext() {
+  CHECK(getter_.get());
+  return getter_->GetURLRequestContext();
+}
+
+void CefResourceContext::set_url_request_context_getter(
+    scoped_refptr<CefURLRequestContextGetter> getter) {
+  DCHECK(!getter_.get());
+  getter_ = getter;
+}