chrome_paths: refactor and sanitize cache directory handling

chrome/common/chrome_paths_win.cc

Index: chrome/common/chrome_paths_win.cc
diff --git a/chrome/common/chrome_paths_win.cc b/chrome/common/chrome_paths_win.cc
index c9fee0fc70f1c124c743c3b7ddf87de5335bf199..74a730d569a55dd9432dba75422c41c62cd855d0 100644
--- a/chrome/common/chrome_paths_win.cc
+++ b/chrome/common/chrome_paths_win.cc
@@ -38,6 +38,11 @@ bool GetChromeFrameUserDataDirectory(FilePath* result) {
   return true;
 }
 
+void GetUserCacheDirectory(const FilePath& profile_dir, FilePath* result) {
+  // This function does more complicated things on Mac/Linux.
+  *result = profile_dir;
+}
+
 bool GetUserDocumentsDirectory(FilePath* result) {
   wchar_t path_buf[MAX_PATH];
   if (FAILED(SHGetFolderPath(NULL, CSIDL_MYDOCUMENTS, NULL,