Enable external popup menu in Blimp, part 2/2.

blimp/engine/session/blimp_engine_session.h

Index: blimp/engine/session/blimp_engine_session.h
diff --git a/blimp/engine/session/blimp_engine_session.h b/blimp/engine/session/blimp_engine_session.h
index 2c064e59f7c8cac8b771e888c1483a01dd5b74f8..637f1019a5cadeb6d0cddec24965a74e5e341243 100644
--- a/blimp/engine/session/blimp_engine_session.h
+++ b/blimp/engine/session/blimp_engine_session.h
@@ -20,6 +20,7 @@
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_view_delegate.h"
 #include "net/base/completion_callback.h"
 #include "ui/base/ime/input_method_observer.h"
 #include "ui/gfx/geometry/size.h"
@@ -35,8 +36,10 @@ class WindowTreeClient;
 
 namespace content {
 class BrowserContext;
+class RenderFrameHost;
 class RenderViewHost;
 class WebContents;
+struct MenuItem;
 }
 
 namespace gfx {
@@ -72,6 +75,7 @@ class BlimpEngineSession
     : public BlimpMessageProcessor,
       public content::WebContentsDelegate,
       public content::WebContentsObserver,
+      public content::WebContentsViewDelegate,
       public ui::InputMethodObserver,
       public EngineRenderWidgetFeature::RenderWidgetMessageDelegate,
       public PageLoadTrackerClient {
@@ -164,6 +168,17 @@ class BlimpEngineSession
                              content::RenderViewHost* new_host) override;
   void RenderViewDeleted(content::RenderViewHost* render_view_host) override;
 
+  // content::WebContentsViewDelegate
+  void ShowPopupMenu(content::RenderFrameHost* render_frame_host,
+                     const gfx::Rect& bounds,
+                     int item_height,
+                     double item_font_size,
+                     int selected_item,
+                     const std::vector<content::MenuItem>& items,
+                     bool right_aligned,
+                     bool allow_multiple_selection) override;
+  void HidePopupMenu() override;
+
   // PageLoadTrackerClient implementation.
   void SendPageLoadStatusUpdate(PageLoadStatus load_status) override;