Fix nullptr deref in maybeRenderFallbackContent()

third_party/WebKit/public/web/WebLocalFrame.h

Index: third_party/WebKit/public/web/WebLocalFrame.h
diff --git a/third_party/WebKit/public/web/WebLocalFrame.h b/third_party/WebKit/public/web/WebLocalFrame.h
index 5242affddc5bbb0181c92b587b46240297465f3b..4837dc464f30b4033061a807bf1d17faf4d32f8e 100644
--- a/third_party/WebKit/public/web/WebLocalFrame.h
+++ b/third_party/WebKit/public/web/WebLocalFrame.h
@@ -153,9 +153,14 @@ class WebLocalFrame : public WebFrame {
                         WebHistoryLoadType = kWebHistoryDifferentDocumentLoad,
                         bool is_client_redirect = false) = 0;
 
-  // On load failure, attempts to make frame's parent rendering fallback content
-  // and stop this frame loading.
-  virtual bool MaybeRenderFallbackContent(const WebURLError&) const = 0;
+  // On load failure, attempts to make frame's parent render fallback content.
+  enum FallbackContentResult {
+    NoFallbackContent,

[Charlie Reis, 2017/04/12 22:05:22]

Comment: An error page should be shown instead of fallback content.

[Nate Chapin, 2017/04/13 17:32:22]

Done.

+    NoLoadInProgress,

[Charlie Reis, 2017/04/12 22:05:22]

Comment: Something else committed instead, so no error page or fallback content
is needed.

[Nate Chapin, 2017/04/13 17:32:21]

Done.

+    FallbackRendered

[Charlie Reis, 2017/04/12 22:05:22]

Comment: Fallback content was shown so no error page should be displayed.

[Nate Chapin, 2017/04/13 17:32:21]

Done.

+  };
+  virtual FallbackContentResult MaybeRenderFallbackContent(
+      const WebURLError&) const = 0;
 
   // Called when a navigation is blocked because a Content Security Policy (CSP)
   // is infringed.