[Favicon] Add new fallback icon rendering flow.

chrome/common/favicon/favicon_url_parser.cc

 // Copyright 2013 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/favicon_url_parser.h"
 
 #include "base/strings/string_number_conversions.h"
 #include "components/favicon_base/favicon_types.h"
 #include "net/url_request/url_request.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
 // "chrome/browser/ui/webui/favicon_source.h" for a description of
 // what each does.
+const char kFallbackParameter[] = "fallback/";
 const char kIconURLParameter[] = "iconurl/";
 const char kLargestParameter[] = "largest/";
 const char kOriginParameter[] = "origin/";
 const char kSizeParameter[] = "size/";
 
 // 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 ParseFaviconPath(const std::string& path,
                       int icon_types,
                       ParsedFaviconPath* parsed) {
   parsed->is_icon_url = false;
   parsed->url = "";
   parsed->size_in_dip = gfx::kFaviconSize;
   parsed->device_scale_factor = 1.0f;
   parsed->path_index = std::string::npos;
+  parsed->fallback_specs_builder.reset(nullptr);
 
   if (path.empty())
     return false;
 
   size_t parsed_index = 0;
   if (HasSubstringAt(path, parsed_index, kLargestParameter)) {
     parsed_index += strlen(kLargestParameter);
     parsed->size_in_dip = 0;
   } else if (HasSubstringAt(path, parsed_index, kSizeParameter)) {
     parsed_index += strlen(kSizeParameter);
@@ skipping 32 matching lines @@
     // - favicons of sizes "gfx::kFaviconSize * scale factor" px of type FAVICON
     //   where scale factor is one of FaviconUtil::GetFaviconScales().
     // - the largest TOUCH_ICON / TOUCH_PRECOMPOSED_ICON
     if (parsed->size_in_dip != gfx::kFaviconSize &&
         icon_types == favicon_base::FAVICON)
       return false;
 
     parsed_index = slash + 1;
   }
 
+  if (HasSubstringAt(path, parsed_index, kFallbackParameter)) {
+    parsed_index += strlen(kFallbackParameter);
+    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);
+    parsed->fallback_specs_builder.reset(
+        new favicon_base::FallbackIconSpecsBuilder());
+    if (!parsed->fallback_specs_builder->Parse(fallback_str))
+      return false;  // Parse failed.
+    parsed_index = slash + 1;
+  }
+
   if (HasSubstringAt(path, parsed_index, kIconURLParameter)) {
     parsed_index += strlen(kIconURLParameter);
     parsed->is_icon_url = true;
     parsed->url = path.substr(parsed_index);
-  } else {
+  } else if (HasSubstringAt(path, parsed_index, kOriginParameter)) {
     // URL requests prefixed with "origin/" are converted to a form with an
     // empty path and a valid scheme. (e.g., example.com -->
     // http://example.com/ or http://example.com/a --> http://example.com/)
-    if (HasSubstringAt(path, parsed_index, kOriginParameter)) {
-      parsed_index += strlen(kOriginParameter);
-      std::string possibly_invalid_url = path.substr(parsed_index);
+    parsed_index += strlen(kOriginParameter);
+    std::string possibly_invalid_url = path.substr(parsed_index);
 
-      // If the URL does not specify a scheme (e.g., example.com instead of
-      // http://example.com), add "http://" as a default.
-      if (!GURL(possibly_invalid_url).has_scheme())
-        possibly_invalid_url = "http://" + possibly_invalid_url;
+    // If the URL does not specify a scheme (e.g., example.com instead of
+    // http://example.com), add "http://" as a default.
+    if (!GURL(possibly_invalid_url).has_scheme())
+      possibly_invalid_url = "http://" + possibly_invalid_url;
 
-      // Strip the path beyond the top-level domain.
-      parsed->url = GURL(possibly_invalid_url).GetOrigin().spec();
-    } else {
-      parsed->url = path.substr(parsed_index);
-    }
+    // Strip the path beyond the top-level domain.
+    parsed->url = GURL(possibly_invalid_url).GetOrigin().spec();
+  } else {
+    parsed->url = path.substr(parsed_index);
   }
 
   // The parsed index needs to be returned in order to allow Instant Extended
   // to translate favicon URLs using advanced parameters.
   // Example:
   //   "chrome-search://favicon/size/16@2x/<renderer-id>/<most-visited-id>"
   // would be translated to:
   //   "chrome-search://favicon/size/16@2x/<most-visited-item-with-given-id>".
   parsed->path_index = parsed_index;
   return true;
 }
 
 }  // namespace chrome