Implement PluginServiceFilterQt

Let Chromium know about the status of plugin availability from
WebEngineSettings. This way it can decide whether the response is
a download and it has more benefits:
- It doesn't have to start a new load request to download a PDF file,
it just treats the original response accordingly.
- Fixes websites which are protected from cross-domain requests (e.g. by
checking the Referer header) and/or redirecting requests for PDFs.
Calling DownloadManager "manually" and not passing the original request
headers did not work when the server relied on them.

Task-number: QTBUG-78114
Change-Id: I8cfa90c211418001c60c4b2f0f8818ee453101fc
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 3 insertions, 6 deletions

diff --git a/src/core/net/plugin_response_interceptor_url_loader_throttle.cpp b/src/core/net/plugin_response_interceptor_url_loader_throttle.cpp
index 326bdabb1..d868e4f54 100644
--- a/src/core/net/plugin_response_interceptor_url_loader_throttle.cpp
+++ b/src/core/net/plugin_response_interceptor_url_loader_throttle.cpp
@@ -91,12 +91,9 @@ void PluginResponseInterceptorURLLoaderThrottle::WillProcessResponse(const GURL
     WebEngineSettings *settings = contentsDelegate->webEngineSettings();
     if (!settings->testAttribute(WebEngineSettings::PdfViewerEnabled)
         || !settings->testAttribute(WebEngineSettings::PluginsEnabled)) {
-        // If the applications has been set up to always download PDF files to open them in an
-        // external viewer, trigger the download.
-        std::unique_ptr<download::DownloadUrlParameters> params(
-                content::DownloadRequestUtils::CreateDownloadForWebContentsMainFrame(web_contents, response_url,
-                                                                                     MISSING_TRAFFIC_ANNOTATION));
-        content::BrowserContext::GetDownloadManager(web_contents->GetBrowserContext())->DownloadUrl(std::move(params));
+        // PluginServiceFilterQt will inform the URLLoader about the disabled state of plugins
+        // and we can expect the download to be triggered automatically. It's unnecessary to
+        // go further and start the guest view embedding process.
         return;
     }