Fix for Incomplete context menu shown in PDF.

components/renderer_context_menu/render_view_context_menu_base.cc

Index: components/renderer_context_menu/render_view_context_menu_base.cc
diff --git a/components/renderer_context_menu/render_view_context_menu_base.cc b/components/renderer_context_menu/render_view_context_menu_base.cc
index cda6c4667aef1908774a90842753fd62598a7b95..3cdf8a326a08a1478e2bd1171c6cbf9d47c56453 100644
--- a/components/renderer_context_menu/render_view_context_menu_base.cc
+++ b/components/renderer_context_menu/render_view_context_menu_base.cc
@@ -15,6 +15,9 @@
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/menu_item.h"
+#if defined(ENABLE_EXTENSIONS)
+#include "extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.h"
+#endif
 #include "third_party/WebKit/public/web/WebContextMenuData.h"
 
 using blink::WebContextMenuData;
@@ -126,6 +129,17 @@ void AddCustomItemsToMenu(const std::vector<content::MenuItem>& items,
   }
 }
 
+content::WebContents* GetWebContentsToUse(content::WebContents* web_contents) {
+// If we're viewing in a MimeHandlerViewGuest, use its embedder WebContents.
+#if defined(ENABLE_EXTENSIONS)
+  auto guest_view =
+      extensions::MimeHandlerViewGuest::FromWebContents(web_contents);
+  if (guest_view)
+    return guest_view->embedder_web_contents();
+#endif
+  return web_contents;
+}
+
 }  // namespace
 
 // static
@@ -155,6 +169,7 @@ RenderViewContextMenuBase::RenderViewContextMenuBase(
     const content::ContextMenuParams& params)
     : params_(params),
       source_web_contents_(WebContents::FromRenderFrameHost(render_frame_host)),
+      embedded_web_contents_(GetWebContentsToUse(source_web_contents_)),
       browser_context_(source_web_contents_->GetBrowserContext()),
       menu_model_(this),
       render_frame_id_(render_frame_host->GetRoutingID()),