'View source code' option should be disabled in context menu for 'Paper Toolbar' of 'Pdf Viewer"

chrome/browser/renderer_context_menu/render_view_context_menu.cc

Index: chrome/browser/renderer_context_menu/render_view_context_menu.cc
diff --git a/chrome/browser/renderer_context_menu/render_view_context_menu.cc b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
index 58c38603bc9b9e6ae64344d07ccfbd529ca08126..9d0170fdba56b8ecc0800ea910c3a241bb5d1168 100644
--- a/chrome/browser/renderer_context_menu/render_view_context_menu.cc
+++ b/chrome/browser/renderer_context_menu/render_view_context_menu.cc
@@ -1153,6 +1153,10 @@ bool RenderViewContextMenu::IsCommandIdEnabled(int id) const {
 
     case IDC_VIEW_SOURCE:
     case IDC_CONTENT_CONTEXT_VIEWFRAMESOURCE:
+      if (!!extensions::MimeHandlerViewGuest::FromWebContents(
+              source_web_contents_)) {
+        return false;
+      }
       return (params_.media_type != WebContextMenuData::MediaTypePlugin) &&
              embedder_web_contents_->GetController().CanViewSource();