Provide a way to obtain WebLocalFrameBase from a LocalFrame.

third_party/WebKit/Source/core/page/ChromeClient.h

Index: third_party/WebKit/Source/core/page/ChromeClient.h
diff --git a/third_party/WebKit/Source/core/page/ChromeClient.h b/third_party/WebKit/Source/core/page/ChromeClient.h
index 343eb977009896920ed82ef037545a246ac5c432..48e803a22358aa477643e872982dc5bdfb826940 100644
--- a/third_party/WebKit/Source/core/page/ChromeClient.h
+++ b/third_party/WebKit/Source/core/page/ChromeClient.h
@@ -77,6 +77,7 @@ class WebFrameScheduler;
 class WebImage;
 class WebLayer;
 class WebLayerTreeView;
+class WebLocalFrameBase;
 
 struct CompositedSelection;
 struct DateTimeChooserParameters;
@@ -352,6 +353,10 @@ class CORE_EXPORT ChromeClient : public PlatformChromeClient {
 
   virtual WebLayerTreeView* GetWebLayerTreeView(LocalFrame*) { return nullptr; }
 
+  virtual WebLocalFrameBase* GetWebLocalFrameBase(LocalFrame*) {
+    return nullptr;
+  }
+
   DECLARE_TRACE();
 
  protected: