Move some XDG code from chrome to base.

chrome/browser/profile.cc

Index: chrome/browser/profile.cc
===================================================================
--- chrome/browser/profile.cc	(revision 33536)
+++ chrome/browser/profile.cc	(working copy)
@@ -608,10 +608,23 @@
       base_cache_path_ = user_cache_path;
     }
   }
+#elif defined(OS_POSIX)  // Posix minus Mac.
+  // See http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
+  // for a spec on where cache files go.  The net effect for most systems is we
+  // use ~/.cache/chromium/ for Chromium and ~/.cache/google-chrome/ for
+  // official builds.
+  if (!PathService::IsOverridden(chrome::DIR_USER_DATA)) {
+#if defined(GOOGLE_CHROME_BUILD)
+    const char kCacheDir[] = "google-chrome";
 #else
-  if (!PathService::IsOverridden(chrome::DIR_USER_DATA))
-    PathService::Get(chrome::DIR_USER_CACHE, &base_cache_path_);
+    const char kCacheDir[] = "chromium";
 #endif
+    PathService::Get(base::DIR_USER_CACHE, &base_cache_path_);
+    base_cache_path_ = base_cache_path_.Append(kCacheDir);
+    if (!file_util::PathExists(base_cache_path_))
+      file_util::CreateDirectory(base_cache_path_);
+  }
+#endif
   if (base_cache_path_.empty())
     base_cache_path_ = path_;