Skip base::string16 if not necessary for WebString <-> ASCII conversion

third_party/WebKit/Source/platform/exported/WebString.cpp

Index: third_party/WebKit/Source/platform/exported/WebString.cpp
diff --git a/third_party/WebKit/Source/platform/exported/WebString.cpp b/third_party/WebKit/Source/platform/exported/WebString.cpp
index 2ad8fa96244c93585fd797059fa56f6723b6a1a5..8e1c81c3d8a1f084d2e545c4ef50af47de77a96e 100644
--- a/third_party/WebKit/Source/platform/exported/WebString.cpp
+++ b/third_party/WebKit/Source/platform/exported/WebString.cpp
@@ -30,6 +30,8 @@
 
 #include "public/platform/WebString.h"
 
+#include "base/strings/string_util.h"
+#include "wtf/text/ASCIIFastPath.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/CString.h"
 #include "wtf/text/StringUTF8Adaptor.h"
@@ -97,6 +99,30 @@ WebString WebString::fromLatin1(const WebLChar* data, size_t length) {
   return String(data, length);
 }
 
+std::string WebString::ascii() const {
+  DCHECK(containsOnlyASCII());
+
+  if (isEmpty())
+    return std::string();
+
+  if (m_private->is8Bit()) {
+    return std::string(reinterpret_cast<const char*>(m_private->characters8()),
+                       m_private->length());
+  }
+
+  return std::string(m_private->characters16(),
+                     m_private->characters16() + m_private->length());
+}
+
+bool WebString::containsOnlyASCII() const {
+  return String(m_private.get()).containsOnlyASCII();
+}
+
+WebString WebString::fromASCII(const std::string& s) {
+  DCHECK(base::IsStringASCII(s));
+  return fromLatin1(s);
+}
+
 bool WebString::equals(const WebString& s) const {
   return equal(m_private.get(), s.m_private.get());
 }