[Favicon] Add new fallback icon rendering flow.

chrome/common/favicon/fallback_icon_url_parser.cc

+// Copyright 2015 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/common/favicon/fallback_icon_url_parser.h"
+
+#include "base/strings/string_number_conversions.h"
+#include "ui/base/webui/web_ui_util.h"
+#include "ui/gfx/favicon_size.h"
+
+namespace {
+
+// Parameters which can be used in chrome://favicon path. See file
+// "fallback_icon_url_parser.h" for a description of what each does.
+const char kSizeParameter[] = "size/";
+const char kStyleParameter[] = "style/";
+
+// Returns true if |search| is a substring of |path| which starts at
+// |start_index|.
+bool HasSubstringAt(const std::string& path,
+                    size_t start_index,
+                    const std::string& search) {
+  return path.compare(start_index, search.length(), search) == 0;
+}
+
+}  // namespace
+
+namespace chrome {
+
+bool ParseFallbackIconPath(const std::string& path,
+                           ParsedFallbackIconPath* parsed) {

[pkotwicz, 2015/01/21 19:44:15]

Can you move the parsing logic to FallbackIconSource? There shouldn't be much
left here once you merge the size parameter into the style parameter.

[huangs, 2015/01/22 01:13:27]

Per other comment, I think size should be a separate parameters, and all
parameter should be named.  Again I won't mind doing some refactoring so common
code between this and ParseFaviconPath() can refer to code in a common library
-- but perhaps this should be done in a separate CL?

[huangs, 2015/01/22 22:51:39]

Moved to ParseFallbackIconPath(), per discussion.

+  DCHECK(parsed);
+  parsed->url = "";
+  parsed->size_in_dip = gfx::kFaviconSize;
+  parsed->device_scale_factor = 1.0f;
+  parsed->style_builder.Reset();
+
+  if (path.empty())
+    return false;
+
+  size_t parsed_index = 0;
+  if (HasSubstringAt(path, parsed_index, kSizeParameter)) {
+    parsed_index += strlen(kSizeParameter);
+    size_t slash = path.find("/", parsed_index);
+    if (slash == std::string::npos)
+      return false;
+    size_t scale_delimiter = path.find("@", parsed_index);
+    std::string size_str;
+    std::string scale_str;
+    if (scale_delimiter == std::string::npos) {
+      // Support the legacy size format of 'size/aa/' where 'aa' is the desired
+      // size in DIP for the sake of not regressing the extensions which use it.
+      size_str = path.substr(parsed_index, slash - parsed_index);
+    } else {
+      size_str = path.substr(parsed_index, scale_delimiter - parsed_index);
+      scale_str = path.substr(scale_delimiter + 1,
+                              slash - scale_delimiter - 1);
+    }
+
+    if (!base::StringToInt(size_str, &parsed->size_in_dip))
+      return false;
+    if (!scale_str.empty())
+      webui::ParseScaleFactor(scale_str, &parsed->device_scale_factor);
+    parsed_index = slash + 1;
+  }
+
+  if (HasSubstringAt(path, parsed_index, kStyleParameter)) {
+    parsed_index += strlen(kStyleParameter);
+    size_t slash = path.find("/", parsed_index);
+    if (slash == std::string::npos)
+      return false;
+    std::string fallback_str = path.substr(parsed_index, slash - parsed_index);
+    if (!parsed->style_builder.Parse(fallback_str))
+      return false;  // Parse failed.
+    parsed_index = slash + 1;
+  }
+
+  // Extract URL.
+  parsed->url = path.substr(parsed_index);
+  return true;
+}
+
+}  // namespace chrome