Provide an overload to WebView::create that does not require a WebViewClient.

third_party/WebKit/Source/web/WebViewImpl.cpp

Index: third_party/WebKit/Source/web/WebViewImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebViewImpl.cpp b/third_party/WebKit/Source/web/WebViewImpl.cpp
index fdfc0b1b0dbb7e4ad7b41a94f1517ee5198219a0..350d7a33ba7449eb826aabebf6570368837abe4d 100644
--- a/third_party/WebKit/Source/web/WebViewImpl.cpp
+++ b/third_party/WebKit/Source/web/WebViewImpl.cpp
@@ -271,18 +271,35 @@ class ColorOverlay final : public PageOverlay::Delegate {
   WebColor m_color;
 };
 
+class DetachedWebViewClient : public WebViewClient {
+ public:
+  virtual ~DetachedWebViewClient() {}
+};
+
 }  // namespace
 
 // WebView ----------------------------------------------------------------
 
+WebView* WebView::create(WebPageVisibilityState visibilityState) {
+  return WebViewImpl::create(visibilityState);
+}
+
 WebView* WebView::create(WebViewClient* client,
                          WebPageVisibilityState visibilityState) {
+  DCHECK(client) << "A valid WebViewClient must be supplied.";
   // Pass the WebViewImpl's self-reference to the caller.
   return WebViewImpl::create(client, visibilityState);
 }
 
+WebViewImpl* WebViewImpl::create(WebPageVisibilityState visibilityState) {
+  DEFINE_STATIC_LOCAL(DetachedWebViewClient, detachedWebViewClient, ());
+  return adoptRef(new WebViewImpl(&detachedWebViewClient, visibilityState))
+      .leakRef();
+}
+
 WebViewImpl* WebViewImpl::create(WebViewClient* client,
                                  WebPageVisibilityState visibilityState) {
+  DCHECK(client) << "A valid WebViewClient must be supplied.";
   // Pass the WebViewImpl's self-reference to the caller.
   return adoptRef(new WebViewImpl(client, visibilityState)).leakRef();
 }