Replace the index mapping of wallpaper picker UI and hard coded wallpaper index in C++

chrome/common/url_constants.cc

Index: chrome/common/url_constants.cc
diff --git a/chrome/common/url_constants.cc b/chrome/common/url_constants.cc
index bd6f7ec274c1e22b6fa49346e0acb275e9548a45..61b460277e3df882aeefe81dc0da396c1bf41dc0 100644
--- a/chrome/common/url_constants.cc
+++ b/chrome/common/url_constants.cc
@@ -95,6 +95,7 @@ const char kChromeUISlideshowURL[] = "chrome://slideshow/";
 const char kChromeUISystemInfoURL[] = "chrome://system/";
 const char kChromeUITermsOemURL[] = "chrome://terms/oem";
 const char kChromeUIUserImageURL[] = "chrome://userimage/";
+const char kChromeUIWallpaperThumbnailURL[] = "chrome://wallpaper/";
 #endif
 
 #if defined(USE_ASH)
@@ -223,6 +224,7 @@ const char kChromeUISimUnlockHost[] = "sim-unlock";
 const char kChromeUISlideshowHost[] = "slideshow";
 const char kChromeUISystemInfoHost[] = "system";
 const char kChromeUIUserImageHost[] = "userimage";
+const char kChromeUIWallpaperThumbnailHost[] = "wallpaper";
 
 const char kChromeUIMenu[] = "menu";
 const char kChromeUINetworkMenu[] = "network-menu";