Make static KURLs thread safe

third_party/WebKit/Source/platform/weborigin/KURL.cpp

Index: third_party/WebKit/Source/platform/weborigin/KURL.cpp
diff --git a/third_party/WebKit/Source/platform/weborigin/KURL.cpp b/third_party/WebKit/Source/platform/weborigin/KURL.cpp
index 3b0af2cc8e5acb07bde24601b32f8526e9f64902..3fd2f13eb7d1726f1302ec28911ec96008a14c75 100644
--- a/third_party/WebKit/Source/platform/weborigin/KURL.cpp
+++ b/third_party/WebKit/Source/platform/weborigin/KURL.cpp
@@ -44,6 +44,8 @@
 
 namespace blink {
 
+const char kAboutBlankUrl[] = "about:blank";
+
 static const int maximumValidPortNumber = 0xFFFE;
 static const int invalidPortNumber = 0xFFFF;
 
@@ -172,21 +174,17 @@ bool protocolIsJavaScript(const String& url) {
 }
 
 const KURL& blankURL() {
-  DEFINE_STATIC_LOCAL(KURL, staticBlankURL, (ParsedURLString, "about:blank"));
+  DEFINE_STATIC_LOCAL(KURL, staticBlankURL, (ParsedURLString, kAboutBlankUrl));
+  DCHECK(isMainThread());
   return staticBlankURL;
 }
 
 bool KURL::isAboutBlankURL() const {
-  return *this == blankURL();
-}
-
-const KURL& srcdocURL() {
-  DEFINE_STATIC_LOCAL(KURL, staticSrcdocURL, (ParsedURLString, "about:srcdoc"));
-  return staticSrcdocURL;
+  return getString() == kAboutBlankUrl;
 }
 
 bool KURL::isAboutSrcdocURL() const {
-  return *this == srcdocURL();
+  return getString() == "about:srcdoc";
 }
 
 String KURL::elidedString() const {