Fix printing PDF files

Delegate printing task down to the guest WebContents if any is present.
Also update PrintWebViewHelperDelegateQt to find the plugin element
properly for printing.

Task-number: QTBUG-98941
Change-Id: I81004a2275e0870a17565af527b1450472afb24b
Reviewed-by: Michael Brüning <michael.bruning@qt.io>
(cherry picked from commit 455efe7ef204c6cd8de72b9b1f922f1681f58589)
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

3 files changed, 43 insertions, 16 deletions

diff --git a/src/core/renderer/print_web_view_helper_delegate_qt.cpp b/src/core/renderer/print_web_view_helper_delegate_qt.cpp
index beae6ecfa..5dcfaafd6 100644
--- a/src/core/renderer/print_web_view_helper_delegate_qt.cpp
+++ b/src/core/renderer/print_web_view_helper_delegate_qt.cpp
@@ -43,11 +43,17 @@
 
 #include "content/public/renderer/render_frame.h"
 #include "content/public/renderer/render_view.h"
+#include "extensions/buildflags/buildflags.h"
 #include "extensions/common/constants.h"
 #include "third_party/blink/public/web/web_document.h"
 #include "third_party/blink/public/web/web_element.h"
 #include "third_party/blink/public/web/web_local_frame.h"
 
+#if BUILDFLAG(ENABLE_EXTENSIONS)
+#include "chrome/common/webui_url_constants.h"
+#include "extensions/common/constants.h"
+#endif  // BUILDFLAG(ENABLE_EXTENSIONS)
+
 #include "print_web_view_helper_delegate_qt.h"
 #include "web_engine_library_info.h"
 
@@ -56,14 +62,23 @@ PrintWebViewHelperDelegateQt::~PrintWebViewHelperDelegateQt() {}
 
 blink::WebElement PrintWebViewHelperDelegateQt::GetPdfElement(blink::WebLocalFrame *frame)
 {
+#if BUILDFLAG(ENABLE_EXTENSIONS)
     GURL url = frame->GetDocument().Url();
-    if (url.SchemeIs(extensions::kExtensionScheme) && url.host() == extension_misc::kPdfExtensionId) {
+    bool inside_print_preview = url.GetOrigin() == chrome::kChromeUIPrintURL;
+    bool inside_pdf_extension = url.SchemeIs(extensions::kExtensionScheme) &&
+                                url.host_piece() == extension_misc::kPdfExtensionId;
+    if (inside_print_preview || inside_pdf_extension) {
         // <object> with id="plugin" is created in
-        // chrome/browser/resources/pdf/pdf.js.
-        auto plugin_element = frame->GetDocument().GetElementById("plugin");
-        CHECK(!plugin_element.IsNull());
-        return plugin_element;
+        // chrome/browser/resources/pdf/pdf_viewer_base.js.
+        auto viewer_element = frame->GetDocument().GetElementById("viewer");
+        if (!viewer_element.IsNull() && !viewer_element.ShadowRoot().IsNull()) {
+            auto plugin_element = viewer_element.ShadowRoot().QuerySelector("#plugin");
+            if (!plugin_element.IsNull())
+                return plugin_element;
+        }
+        NOTREACHED();
     }
+#endif  // BUILDFLAG(ENABLE_EXTENSIONS)
     return blink::WebElement();
 }
 
diff --git a/src/core/web_contents_adapter.cpp b/src/core/web_contents_adapter.cpp
index 2cd48907b..5b81bd3fc 100644
--- a/src/core/web_contents_adapter.cpp
+++ b/src/core/web_contents_adapter.cpp
@@ -1332,10 +1332,13 @@ void WebContentsAdapter::printToPDF(const QPageLayout &pageLayout, const QString
     PrintViewManagerQt::PrintToPDFFileCallback callback = base::Bind(&callbackOnPdfSavingFinished,
                                                                 m_adapterClient,
                                                                 filePath);
-    PrintViewManagerQt::FromWebContents(m_webContents.get())->PrintToPDFFileWithCallback(pageLayout,
-                                                                                   true,
-                                                                                   filePath,
-                                                                                   callback);
+    content::WebContents *webContents = m_webContents.get();
+    if (content::WebContents *guest = guestWebContents())
+        webContents = guest;
+    PrintViewManagerQt::FromWebContents(webContents)->PrintToPDFFileWithCallback(pageLayout,
+                                                                                 true,
+                                                                                 filePath,
+                                                                                 callback);
 #endif // QT_CONFIG(webengine_printing_and_pdf)
 }
 
@@ -1348,10 +1351,13 @@ quint64 WebContentsAdapter::printToPDFCallbackResult(const QPageLayout &pageLayo
     PrintViewManagerQt::PrintToPDFCallback callback = base::Bind(&callbackOnPrintingFinished,
                                                                  m_adapterClient,
                                                                  m_nextRequestId);
-    PrintViewManagerQt::FromWebContents(m_webContents.get())->PrintToPDFWithCallback(pageLayout,
-                                                                               colorMode,
-                                                                               useCustomMargins,
-                                                                               callback);
+    content::WebContents *webContents = m_webContents.get();
+    if (content::WebContents *guest = guestWebContents())
+        webContents = guest;
+    PrintViewManagerQt::FromWebContents(webContents)->PrintToPDFWithCallback(pageLayout,
+                                                                             colorMode,
+                                                                             useCustomMargins,
+                                                                             callback);
     return m_nextRequestId++;
 #else
     Q_UNUSED(pageLayout);
@@ -1444,6 +1450,12 @@ content::WebContents *WebContentsAdapter::webContents() const
     return m_webContents.get();
 }
 
+content::WebContents *WebContentsAdapter::guestWebContents() const
+{
+    std::vector<content::WebContents *> innerWebContents = m_webContents->GetInnerWebContents();
+    return !innerWebContents.empty() ? innerWebContents[0] : nullptr;
+}
+
 #if QT_CONFIG(webengine_webchannel)
 QWebChannel *WebContentsAdapter::webChannel() const
 {
@@ -1551,9 +1563,8 @@ void WebContentsAdapter::startDragging(QObject *dragSource, const content::DropD
             // dropping data into them. We don't even try to support dropping into PDF input fields,
             // since it's not working in Chrome right now.
             content::WebContents *targetWebContents = m_webContents.get();
-            std::vector<content::WebContents *> innerWebContents = m_webContents->GetInnerWebContents();
-            if (!innerWebContents.empty())
-                targetWebContents = innerWebContents[0];
+            if (content::WebContents *guest = guestWebContents())
+                targetWebContents = guest;
 
             content::RenderViewHost *rvh = targetWebContents->GetRenderViewHost();
             if (rvh) {
diff --git a/src/core/web_contents_adapter.h b/src/core/web_contents_adapter.h
index 78dda6060..ba02a0418 100644
--- a/src/core/web_contents_adapter.h
+++ b/src/core/web_contents_adapter.h
@@ -242,6 +242,7 @@ public:
     // meant to be used within WebEngineCore only
     void initialize(content::SiteInstance *site);
     content::WebContents *webContents() const;
+    content::WebContents *guestWebContents() const;
     void updateRecommendedState();
     void setRequestInterceptor(QWebEngineUrlRequestInterceptor *interceptor);
     QWebEngineUrlRequestInterceptor* requestInterceptor() const;