Make ResolveRelative work with all hierarchical URLs.

src/url_canon_unittest.cc

 // Copyright 2007, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 2018 matching lines @@
       // Filesystem URL tests; filesystem URLs are only valid and relative if
       // they have no scheme, e.g. "./index.html".  There's no valid equivalent
       // to http:index.html.
     {"filesystem:http://host/t/path", true, false, "filesystem:http://host/t/path2", true, false, false, NULL},
     {"filesystem:http://host/t/path", true, false, "filesystem:https://host/t/path2", true, false, false, NULL},
     {"filesystem:http://host/t/path", true, false, "http://host/t/path2", true, false, false, NULL},
     {"http://host/t/path", true, false, "filesystem:http://host/t/path2", true, false, false, NULL},
     {"filesystem:http://host/t/path", true, false, "./path2", true, true, true, "filesystem:http://host/t/path2"},
     {"filesystem:http://host/t/path/", true, false, "path2", true, true, true, "filesystem:http://host/t/path/path2"},
     {"filesystem:http://host/t/path", true, false, "filesystem:http:path2", true, false, false, NULL},
+      // Absolute URLs are still not relative to a non-standard base URL.
+    {"about:blank", false, false, "http://X/A", true, false, true, ""},
+    {"about:blank", false, false, "content://content.Provider/", true, false, true, ""},
   };
 
   for (size_t i = 0; i < ARRAYSIZE(rel_cases); i++) {
     const RelativeCase& cur_case = rel_cases[i];
 
     url_parse::Parsed parsed;
     int base_len = static_cast<int>(strlen(cur_case.base));
     if (cur_case.is_base_file)
       url_parse::ParseFileURL(cur_case.base, base_len, &parsed);
     else if (cur_case.is_base_hier)
@@ skipping 72 matching lines @@
   url_canon::StdStringCanonOutput repl_output(&repl_str);
   url_canon::ReplaceFileURL(src, parsed, repl, NULL, &repl_output, &repl_parsed);
   repl_output.Complete();
 
   // Generate the expected string and check.
   std::string expected("file:///foo?");
   for (size_t i = 0; i < new_query.length(); i++)
     expected.push_back('a');
   EXPECT_TRUE(expected == repl_str);
 }