Remove ResourceError::is_null_

It should consult |domain_| to check nullity.

Bug: 748491
Change-Id: I99a37ecc145c873c0ab191d005a1f15b47aeed7a
Reviewed-on: https://chromium-review.googlesource.com/576015Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
Commit-Queue: Yutaka Hirano <yhirano@chromium.org>
Cr-Commit-Position: refs/heads/master@{#490712}

third_party/WebKit/Source/platform/loader/fetch/ResourceError.cpp

@@ -78,7 +78,6 @@ ResourceError ResourceError::Copy() const {
   error_copy.error_code_ = error_code_;
   error_copy.failing_url_ = failing_url_.Copy();
   error_copy.localized_description_ = localized_description_.IsolatedCopy();
-  error_copy.is_null_ = is_null_;
   error_copy.is_access_check_ = is_access_check_;
   error_copy.was_ignored_by_handler_ = was_ignored_by_handler_;
   return error_copy;
@@ -88,9 +87,6 @@ bool ResourceError::Compare(const ResourceError& a, const ResourceError& b) {
   if (a.IsNull() && b.IsNull())
     return true;
 
-  if (a.IsNull() || b.IsNull())
-    return false;
-
   if (a.GetDomain() != b.GetDomain())
     return false;
 

third_party/WebKit/Source/platform/loader/fetch/ResourceError.h

@@ -72,14 +72,15 @@ class PLATFORM_EXPORT ResourceError final {
       : domain_(domain),
         error_code_(error_code),
         failing_url_(failing_url),
-        localized_description_(localized_description),
-        is_null_(false) {}
+        localized_description_(localized_description) {
+    DCHECK_NE(domain, Domain::kEmpty);
+  }
 
   // Makes a deep copy. Useful for when you need to use a ResourceError on
   // another thread.
   ResourceError Copy() const;
 
-  bool IsNull() const { return is_null_; }
+  bool IsNull() const { return domain_ == Domain::kEmpty; }
 
   Domain GetDomain() const { return domain_; }
   int ErrorCode() const { return error_code_; }
@@ -126,7 +127,6 @@ class PLATFORM_EXPORT ResourceError final {
   int error_code_ = 0;
   KURL failing_url_;
   String localized_description_;
-  bool is_null_ = true;
   bool is_access_check_ = false;
   bool stale_copy_in_cache_ = false;
   bool was_ignored_by_handler_ = false;

third_party/WebKit/Source/platform/testing/URLTestHelpers.cpp

@@ -84,6 +84,7 @@ void RegisterMockedErrorURLLoad(const WebURL& full_url) {
   response.SetLoadTiming(timing);
 
   WebURLError error;
+  error.domain = WebURLError::Domain::kTest;
   error.reason = 404;
   Platform::Current()->GetURLLoaderMockFactory()->RegisterErrorURL(
       full_url, response, error);