Fix dangling raw_ptr errors and related issues (see #3239)

- Use raw_ptr in class container fields.
- Use defined lifespan for StreamReaderURLLoader.
- Fix lifespan assumptions for WebContents/RFH usage.

libcef/browser/alloy/chrome_browser_process_alloy.cc

@@ -154,6 +154,7 @@ void ChromeBrowserProcessAlloy::CleanupOnUIThread() {
     }
   }
 
+  os_crypt_async_.reset();
   local_state_.reset();
   browser_policy_connector_.reset();
   background_printing_manager_.reset();