Suggest about:blank autocompletion from BuiltinProvider.

chrome/browser/autocomplete/builtin_provider.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/autocomplete/builtin_provider.h"
 
 #include <algorithm>
 
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 87 matching lines @@
 #endif
     AddMatch(base::ASCIIToUTF16(chrome::kChromeUIVersionURL),
              base::string16(), styles);
   } else {
     // Match input about: or chrome: URL input against builtin chrome URLs.
     GURL url = URLFixerUpper::FixupURL(base::UTF16ToUTF8(text), std::string());
     // BuiltinProvider doesn't know how to suggest valid ?query or #fragment
     // extensions to chrome: URLs.
     if (url.SchemeIs(content::kChromeUIScheme) && url.has_host() &&
         !url.has_query() && !url.has_ref()) {
+      // Suggest about:blank for substrings, taking URL fixup into account.

[Mark P, 2014/05/29 23:48:05]

Note that this was of doing it will put about:blank before any other
BuiltinProvider inputs that match the input.  i.e., if there were an  about:bee,
the matches would no longer be alphabetic as they were before.
I don't think this is an issue now.  Regardless, consider whether it's worth a
comment or a minor code change to leave things alphabetical.

[msw, 2014/05/30 00:29:49]

It might be considered alphabetical if you're comparing "about:blank" to
"chrome://blob-internals" and "chrome://bookmarks". I don't think it's really
worth a code comment.

[Mark P, 2014/05/30 18:16:41]

Okay.

+      const base::string16 blank_host = base::ASCIIToUTF16("blank");
+      const base::string16 host = base::UTF8ToUTF16(url.host());
+      if (StartsWith(text, base::ASCIIToUTF16(content::kAboutScheme), false) &&
+          StartsWith(blank_host, host, false) && url.path().length() <= 1 &&

[Mark P, 2014/05/29 23:48:05]

nit: parens around binary operator <=

[msw, 2014/05/30 00:29:49]

Done.

+          !EndsWith(text, base::ASCIIToUTF16("/"), false)) {

[Mark P, 2014/05/29 23:48:05]

please comment on the need for this final EndsWith clause.

[msw, 2014/05/30 00:29:49]

Done.

+        ACMatchClassifications styles;
+        styles.push_back(ACMatchClassification(0, kMatch));
+        base::string16 match = base::ASCIIToUTF16(content::kAboutBlankURL);
+        const size_t corrected_input_length = 6 + host.length();

[Mark P, 2014/05/29 23:48:05]

comment on the "6"
(and if it's 6 because this is the length of "about:" then why don't you
actually do length of kAboutScheme + ":"?)

[msw, 2014/05/30 00:29:49]

Done (used kAboutSchemeLength + 1) and added a comment.

+        if (blank_host.length() > host.length())
+          styles.push_back(ACMatchClassification(corrected_input_length, kUrl));
+        AddMatch(match, match.substr(corrected_input_length), styles);
+      }
+
       // Include the path for sub-pages (e.g. "chrome://settings/browser").
       base::string16 host_and_path = base::UTF8ToUTF16(url.host() + url.path());
       base::TrimString(host_and_path, base::ASCIIToUTF16("/").c_str(),
                        &host_and_path);
       size_t match_length = kChrome.length() + host_and_path.length();
       for (Builtins::const_iterator i(builtins_.begin());
           (i != builtins_.end()) && (matches_.size() < kMaxMatches); ++i) {
         if (StartsWith(*i, host_and_path, false)) {
           ACMatchClassifications styles;
           // Highlight the "chrome://" scheme, even for input "about:foo".
@@ skipping 26 matching lines @@
                                const ACMatchClassifications& styles) {
   AutocompleteMatch match(this, kRelevance, false,
                           AutocompleteMatchType::NAVSUGGEST);
   match.fill_into_edit = match_string;
   match.inline_autocompletion = inline_completion;
   match.destination_url = GURL(match_string);
   match.contents = match_string;
   match.contents_class = styles;
   matches_.push_back(match);
 }