[DevTools] Pause input events in WebFrameWidgetImpl while debugging.

Source/web/WebViewImpl.h

Index: Source/web/WebViewImpl.h
diff --git a/Source/web/WebViewImpl.h b/Source/web/WebViewImpl.h
index 09a8aa9e736799f56ca80cf4f47e67c9f2ec478a..2647f97bd7690ae58a6d5040ce5eea7e8be11b28 100644
--- a/Source/web/WebViewImpl.h
+++ b/Source/web/WebViewImpl.h
@@ -59,6 +59,7 @@
 #include "web/PageWidgetDelegate.h"
 #include "web/SpellCheckerClientImpl.h"
 #include "web/StorageClientImpl.h"
+#include "wtf/HashSet.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/Vector.h"
@@ -93,6 +94,7 @@ class WebViewImpl final : public WebView
     , public PageWidgetEventHandler {
 public:
     static WebViewImpl* create(WebViewClient*);
+    static HashSet<WebViewImpl*>& allInstances();
 
     // WebWidget methods:
     virtual void close() override;