Add schema chrome-extension-resource:// for extension resources

chrome/common/extensions/extension_file_util.cc

Index: chrome/common/extensions/extension_file_util.cc
diff --git a/chrome/common/extensions/extension_file_util.cc b/chrome/common/extensions/extension_file_util.cc
index 3f9a9b99b307956cbec8ac1bc65eda47d7d31f56..8297c337a437f9d09b406f9f44c6e922ff81adab 100644
--- a/chrome/common/extensions/extension_file_util.cc
+++ b/chrome/common/extensions/extension_file_util.cc
@@ -635,6 +635,26 @@ FilePath ExtensionURLToRelativeFilePath(const GURL& url) {
   return path;
 }
 
+FilePath ExtensionResourceURLToFilePath(const GURL& url, const FilePath& root) {
+  std::string host = net::UnescapeURLComponent(url.host(),
+      net::UnescapeRule::SPACES | net::UnescapeRule::URL_SPECIAL_CHARS);
+  if (host.empty())
+    return FilePath();
+
+  FilePath relative_path = ExtensionURLToRelativeFilePath(url);
+  if (relative_path.empty())
+    return FilePath();
+
+  FilePath path = root.AppendASCII(host).Append(relative_path);
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
+  if (!file_util::PathExists(path) ||
+      !file_util::AbsolutePath(&path) ||
+      !root.IsParent(path)) {
+    return FilePath();
+  }
+  return path;
+}
+
 FilePath GetUserDataTempDir() {
   // We do file IO in this function, but only when the current profile's
   // Temp directory has never been used before, or in a rare error case.