Fix crash on meet.google.com

This site crashes after 0185f41 when it tries to use the
Hangouts extension. Background WebContent of this extension
(and future guest views) doesn't have a corresponding
WebContentsAdapterClient.

Change-Id: I2028372a176a7194bf037093f9364d942bef969a
Reviewed-by: Peter Varga <[email protected]>
Reviewed-by: Allan Sandfeld Jensen <[email protected]>

Author: davidsz

src/core/net/proxying_url_loader_factory_qt.cpp

@@ -236,8 +236,8 @@ QWebEngineUrlRequestInterceptor* InterceptedRequest::getPageInterceptor()
 {
     if (auto wc = webContents()) {
         auto view = static_cast<content::WebContentsImpl *>(wc)->GetView();
-        WebContentsAdapterClient *client = WebContentsViewQt::from(view)->client();
-        return client->webContentsAdapter()->requestInterceptor();
+        if (WebContentsAdapterClient *client = WebContentsViewQt::from(view)->client())
+            return client->webContentsAdapter()->requestInterceptor();
     }
     return nullptr;
 }