Fix a data URL generation code in DeveloperPrivateAPI

"image" is specified as a MIME type but is invalid. We should just omit
the MIME type parameter.

BUG=377409

Review URL: https://codereview.chromium.org/303483006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@273118 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/extensions/api/developer_private/developer_private_api.cc

@@ -101,7 +101,7 @@ GURL GetImageURLFromData(const std::string& contents) {
   base::Base64Encode(contents, &contents_base64);
 
   // TODO(dvh): make use of content::kDataScheme. Filed as crbug/297301.
-  const char kDataURLPrefix[] = "data:image;base64,";
+  const char kDataURLPrefix[] = "data:;base64,";
   return GURL(kDataURLPrefix + contents_base64);
 }