diff --git mime_handler_view_guest.cc mime_handler_view_guest.cc
index 13f7dc3..acbc1ca 100644
--- mime_handler_view_guest.cc
+++ mime_handler_view_guest.cc
@@ -134,6 +134,8 @@ void MimeHandlerViewGuest::CreateWebContents(
   WebContents::CreateParams params(browser_context(),
                                    guest_site_instance.get());
   params.guest_delegate = this;
+  if (delegate_)
+    delegate_->OverrideWebContentsCreateParams(&params);
   callback.Run(WebContents::Create(params));
 }
 
@@ -158,6 +160,30 @@ bool MimeHandlerViewGuest::ZoomPropagatesFromEmbedderToGuest() const {
   return false;
 }
 
+void MimeHandlerViewGuest::OnGuestAttached(
+    content::WebContentsView* guest_view,
+    content::WebContentsView* parent_view) {
+  if (!delegate_ || !delegate_->OnGuestAttached(guest_view, parent_view))
+    BrowserPluginGuestDelegate::OnGuestAttached(guest_view, parent_view);
+}
+
+void MimeHandlerViewGuest::OnGuestDetached(
+    content::WebContentsView* guest_view,
+    content::WebContentsView* parent_view) {
+  if (!delegate_ || !delegate_->OnGuestDetached(guest_view, parent_view))
+    BrowserPluginGuestDelegate::OnGuestDetached(guest_view, parent_view);
+}
+
+void MimeHandlerViewGuest::CreateViewForWidget(
+    content::WebContentsView* guest_view,
+    content::RenderWidgetHost* render_widget_host) {
+  if (!delegate_ ||
+      !delegate_->CreateViewForWidget(guest_view, render_widget_host)) {
+    BrowserPluginGuestDelegate::CreateViewForWidget(guest_view,
+                                                    render_widget_host);
+  }
+}
+
 WebContents* MimeHandlerViewGuest::OpenURLFromTab(
     WebContents* source,
     const content::OpenURLParams& params) {
diff --git mime_handler_view_guest.h mime_handler_view_guest.h
index ef91c24..f849918 100644
--- mime_handler_view_guest.h
+++ mime_handler_view_guest.h
@@ -75,6 +75,15 @@ class MimeHandlerViewGuest :
   bool ShouldHandleFindRequestsForEmbedder() const final;
   bool ZoomPropagatesFromEmbedderToGuest() const final;
 
+  // content::BrowserPluginGuestDelegate implementation
+  void OnGuestAttached(content::WebContentsView* guest_view,
+                       content::WebContentsView* parent_view) override;
+  void OnGuestDetached(content::WebContentsView* guest_view,
+                       content::WebContentsView* parent_view) override;
+  void CreateViewForWidget(
+      content::WebContentsView* guest_view,
+      content::RenderWidgetHost* render_widget_host) override;
+
   // WebContentsDelegate implementation.
   content::WebContents* OpenURLFromTab(
       content::WebContents* source,
diff --git mime_handler_view_guest_delegate.cc mime_handler_view_guest_delegate.cc
index 63b81b8..0f63f48 100644
--- mime_handler_view_guest_delegate.cc
+++ mime_handler_view_guest_delegate.cc
@@ -6,6 +6,24 @@
 
 namespace extensions {
 
+bool MimeHandlerViewGuestDelegate::OnGuestAttached(
+    content::WebContentsView* guest_view,
+    content::WebContentsView* parent_view) {
+  return false;
+}
+
+bool MimeHandlerViewGuestDelegate::OnGuestDetached(
+    content::WebContentsView* guest_view,
+    content::WebContentsView* parent_view) {
+  return false;
+}
+
+bool MimeHandlerViewGuestDelegate::CreateViewForWidget(
+    content::WebContentsView* guest_view,
+    content::RenderWidgetHost* render_widget_host) {
+  return false;
+}
+
 bool MimeHandlerViewGuestDelegate::HandleContextMenu(
     content::WebContents* web_contents,
     const content::ContextMenuParams& params) {
diff --git mime_handler_view_guest_delegate.h mime_handler_view_guest_delegate.h
index e065104d..f68b66c 100644
--- mime_handler_view_guest_delegate.h
+++ mime_handler_view_guest_delegate.h
@@ -6,10 +6,11 @@
 #define EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_
 
 #include "base/macros.h"
+#include "content/public/browser/web_contents.h"
 
 namespace content {
-class WebContents;
 struct ContextMenuParams;
+class RenderWidgetHost;
 }  // namespace content
 
 namespace extensions {
@@ -21,6 +22,21 @@ class MimeHandlerViewGuestDelegate {
  public:
   MimeHandlerViewGuestDelegate() {}
   virtual ~MimeHandlerViewGuestDelegate() {}
+  
+  // Provides an opportunity to supply a custom view implementation.
+  virtual void OverrideWebContentsCreateParams(
+      content::WebContents::CreateParams* params) {}
+
+  // Called when a guest is attached or detached.
+  virtual bool OnGuestAttached(content::WebContentsView* guest_view,
+                               content::WebContentsView* parent_view);
+  virtual bool OnGuestDetached(content::WebContentsView* guest_view,
+                               content::WebContentsView* parent_view);
+
+  // Called to create the view for the widget.
+  virtual bool CreateViewForWidget(
+      content::WebContentsView* guest_view,
+      content::RenderWidgetHost* render_widget_host);
 
   // Handles context menu, or returns false if unhandled.
   virtual bool HandleContextMenu(content::WebContents* web_contents,