Remove methods that modify cookie storage at runtime (see issue #2622).

This change removes cookie and request handler functionality that will not
supported by the NetworkService. Specifically, it is no longer possible to
change cookie storage locations at runime by returning a different
CefCookieManager for an already initialized CefRequestContext. After this change
you will need to use a separate CefRequestContext when creating a CefBrowser if
you require separate cookie storage.

The following methods have been removed:
- CefCookieManager::CreateManager
- CefCookieManager::GetBlockingManager
- CefCookieManager::SetStoragePath
- CefRequestContextHandler::GetCookieManager

The following methods have been renamed:
- CefRequestContext::GetDefaultCookieManager to GetCookieManager.

This change substantially simplifies the network implementation in CEF because
it is no longer necessary to proxy objects that are normally owned by Chromium.
Chromium patches that are no longer necessary will be removed as a follow-up
commit.

To test: Verify that `ceftests --gtest_filter=-PluginTest.*` pass with
NetworkService disabled. Plugin tests will be fixed in a follow-up commit.

include/capi/cef_request_context_handler_capi.h

@@ -33,7 +33,7 @@
 // by hand. See the translator.README.txt file in the tools directory for
 // more information.
 //
-// $hash=03c829d89f0b5b7ab12634fa2f11c4903cd8edb2$
+// $hash=2bf745d270f474b3d5b36fc3fc2fca2b508ec16f$
 //
 
 #ifndef CEF_INCLUDE_CAPI_CEF_REQUEST_CONTEXT_HANDLER_CAPI_H_
@@ -41,7 +41,6 @@
 #pragma once
 
 #include "include/capi/cef_base_capi.h"
-#include "include/capi/cef_cookie_capi.h"
 #include "include/capi/cef_web_plugin_capi.h"
 
 #ifdef __cplusplus
@@ -69,14 +68,6 @@ typedef struct _cef_request_context_handler_t {
       struct _cef_request_context_handler_t* self,
       struct _cef_request_context_t* request_context);
 
-  ///
-  // Called on the browser process IO thread to retrieve the cookie manager. If
-  // this function returns NULL the default cookie manager retrievable via
-  // cef_request_tContext::get_default_cookie_manager() will be used.
-  ///
-  struct _cef_cookie_manager_t*(CEF_CALLBACK* get_cookie_manager)(
-      struct _cef_request_context_handler_t* self);
-
   ///
   // Called on multiple browser process threads before a plugin instance is
   // loaded. |mime_type| is the mime type of the plugin that will be loaded.