Add support for favicon scale factor in WebUI

chrome/browser/ui/webui/ntp/favicon_webui_handler.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/ui/webui/ntp/favicon_webui_handler.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
@@ skipping 65 matching lines @@
       base::Bind(&FaviconWebUIHandler::HandleGetFaviconDominantColor,
                  base::Unretained(this)));
   web_ui()->RegisterMessageCallback("getAppIconDominantColor",
       base::Bind(&FaviconWebUIHandler::HandleGetAppIconDominantColor,
                  base::Unretained(this)));
 }
 
 void FaviconWebUIHandler::HandleGetFaviconDominantColor(const ListValue* args) {
   std::string path;
   CHECK(args->GetString(0, &path));
-  DCHECK(StartsWithASCII(path, "chrome://favicon/size/16/", false)) <<
-      "path is " << path;
-  path = path.substr(arraysize("chrome://favicon/size/16/") - 1);
+  std::string prefix = "chrome://favicon/size/";
+  DCHECK(StartsWithASCII(path, prefix, false)) << "path is " << path;
+  size_t slash = path.find("/", prefix.length());
+  path = path.substr(slash + 1);
 
   std::string dom_id;
   CHECK(args->GetString(1, &dom_id));
 
   FaviconService* favicon_service = FaviconServiceFactory::GetForProfile(
       Profile::FromWebUI(web_ui()), Profile::EXPLICIT_ACCESS);
   if (!favicon_service || path.empty())
     return;
 
   GURL url(path);
@@ skipping 63 matching lines @@
   std::vector<unsigned char> bits;
   if (!gfx::PNGCodec::EncodeBGRASkBitmap(bitmap, true, &bits))
     return;
   scoped_refptr<base::RefCountedStaticMemory> bits_mem(
       new base::RefCountedStaticMemory(&bits.front(), bits.size()));
   scoped_ptr<StringValue> color_value(GetDominantColorCssString(bits_mem));
   StringValue id(extension_id);
   web_ui()->CallJavascriptFunction(
       "ntp.setFaviconDominantColor", id, *color_value);
 }