Fix a DCHECK we hit when a mime type isn't ASCII.

webkit/glue/simple_webmimeregistry_impl.cc

Index: webkit/glue/simple_webmimeregistry_impl.cc
diff --git a/webkit/glue/simple_webmimeregistry_impl.cc b/webkit/glue/simple_webmimeregistry_impl.cc
index 29296ff13151539c3e3bf3ee0874c8f802d24237..63c11653bb25ee23674c39f8f23da075527bed06 100644
--- a/webkit/glue/simple_webmimeregistry_impl.cc
+++ b/webkit/glue/simple_webmimeregistry_impl.cc
@@ -14,18 +14,30 @@
 using WebKit::WebString;
 using WebKit::WebMimeRegistry;
 
+namespace {
+
+// Convert a WebString to ASCII, falling back on an empty string in the case
+// of a non-ASCII string.
+const std::string& AsASCII(const WebString& string) {
+  if (!IsStringASCII(string))
+    return EmptyString();
+  return UTF16ToASCII(string);
+}
+
+}  // namespace
+
 namespace webkit_glue {
 
 WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsImageMIMEType(
     const WebString& mime_type) {
-  if (!net::IsSupportedImageMimeType(UTF16ToASCII(mime_type).c_str()))
+  if (!net::IsSupportedImageMimeType(AsASCII(mime_type).c_str()))
     return WebMimeRegistry::IsNotSupported;
   return WebMimeRegistry::IsSupported;
 }
 
 WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsJavaScriptMIMEType(
     const WebString& mime_type) {
-  if (!net::IsSupportedJavascriptMimeType(UTF16ToASCII(mime_type).c_str()))
+  if (!net::IsSupportedJavascriptMimeType(AsASCII(mime_type).c_str()))
     return WebMimeRegistry::IsNotSupported;
   return WebMimeRegistry::IsSupported;
 }
@@ -33,12 +45,12 @@ WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsJavaScriptMIMET
 WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsMediaMIMEType(
     const WebString& mime_type, const WebString& codecs) {
   // Not supporting the container is a flat-out no.
-  if (!net::IsSupportedMediaMimeType(UTF16ToASCII(mime_type).c_str()))
+  if (!net::IsSupportedMediaMimeType(AsASCII(mime_type).c_str()))
     return IsNotSupported;
 
   // If we don't recognize the codec, it's possible we support it.
   std::vector<std::string> parsed_codecs;
-  net::ParseCodecString(UTF16ToASCII(codecs).c_str(), &parsed_codecs);
+  net::ParseCodecString(AsASCII(codecs).c_str(), &parsed_codecs);
   if (!net::AreSupportedMediaCodecs(parsed_codecs))
     return MayBeSupported;
 
@@ -48,7 +60,7 @@ WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsMediaMIMEType(
 
 WebMimeRegistry::SupportsType SimpleWebMimeRegistryImpl::supportsNonImageMIMEType(
     const WebString& mime_type) {
-  if (!net::IsSupportedNonImageMimeType(UTF16ToASCII(mime_type).c_str()))
+  if (!net::IsSupportedNonImageMimeType(AsASCII(mime_type).c_str()))
     return WebMimeRegistry::IsNotSupported;
   return WebMimeRegistry::IsSupported;
 }
@@ -72,7 +84,7 @@ WebString SimpleWebMimeRegistryImpl::mimeTypeFromFile(
 WebString SimpleWebMimeRegistryImpl::preferredExtensionForMIMEType(
     const WebString& mime_type) {
   FilePath::StringType file_extension;
-  net::GetPreferredExtensionForMimeType(UTF16ToASCII(mime_type),
+  net::GetPreferredExtensionForMimeType(AsASCII(mime_type),
                                         &file_extension);
   return FilePathStringToWebString(file_extension);
 }