Modify fileAtPath stat to track if the call was redirected by chrome_elf.

chrome_elf/create_file/chrome_create_file.cc

Index: chrome_elf/create_file/chrome_create_file.cc
diff --git a/chrome_elf/create_file/chrome_create_file.cc b/chrome_elf/create_file/chrome_create_file.cc
index b6744f3f34d38f5f34967bb4c3da44dc50b7e7d9..161c36137da89bfdd766e2833d5c9ec39ce2468f 100644
--- a/chrome_elf/create_file/chrome_create_file.cc
+++ b/chrome_elf/create_file/chrome_create_file.cc
@@ -43,6 +43,9 @@ PathIsPrefixFunction g_path_is_prefix_func;
 PathFindFileName g_path_find_filename_func;
 SHGetFolderPathFunction g_get_folder_func;
 
+// Record the number of calls we've redirected so far.
+int g_redirect_count = 0;
+
 // Populates the g_*_func pointers to functions which will be used in
 // ShouldBypass(). Chrome_elf cannot have a load-time dependency on shell32 or
 // shlwapi as this would induce a load-time dependency on user32.dll. Instead,
@@ -92,6 +95,7 @@ HANDLE WINAPI CreateFileWRedirect(
     DWORD flags_and_attributes,
     HANDLE template_file) {
   if (ShouldBypass(file_name)) {
+    ++g_redirect_count;
     return CreateFileNTDLL(file_name,
                            desired_access,
                            share_mode,
@@ -110,6 +114,10 @@ HANDLE WINAPI CreateFileWRedirect(
 
 }
 
+int GetRedirectCount() {
+  return g_redirect_count;
+}
+
 HANDLE CreateFileNTDLL(
     LPCWSTR file_name,
     DWORD desired_access,