Implement NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.

third_party/WebKit/Source/core/frame/FrameOwner.h

Index: third_party/WebKit/Source/core/frame/FrameOwner.h
diff --git a/third_party/WebKit/Source/core/frame/FrameOwner.h b/third_party/WebKit/Source/core/frame/FrameOwner.h
index 614932460b72cc3abeac01bd5e9f9dc18b634736..6445c5d068bbc96ad31dcaf2d0b0be7138e3d625 100644
--- a/third_party/WebKit/Source/core/frame/FrameOwner.h
+++ b/third_party/WebKit/Source/core/frame/FrameOwner.h
@@ -39,6 +39,10 @@ class CORE_EXPORT FrameOwner : public GarbageCollectedMixin {
   virtual bool canRenderFallbackContent() const = 0;
   virtual void renderFallbackContent() = 0;
 
+  // Collapses the frame owner, i.e. removes it from the layout of the parent
+  // frame if the owner is an <iframe> element.
+  virtual void setShouldCollapse(bool) {}
+
   virtual ScrollbarMode scrollingMode() const = 0;
   virtual int marginWidth() const = 0;
   virtual int marginHeight() const = 0;