Convert BlockFiles to use FilePath instead of wstring.

net/disk_cache/disk_cache_test_util.h

Index: net/disk_cache/disk_cache_test_util.h
diff --git a/net/disk_cache/disk_cache_test_util.h b/net/disk_cache/disk_cache_test_util.h
index 9e175122a97e9291920a201ee79a8d582823c5d8..24c5567dcf52c3e826c179e7b6780c8c718f0373 100644
--- a/net/disk_cache/disk_cache_test_util.h
+++ b/net/disk_cache/disk_cache_test_util.h
@@ -13,10 +13,14 @@
 #include "base/timer.h"
 #include "net/base/test_completion_callback.h"
 
+class FilePath;
+
 // Re-creates a given test file inside the cache test folder.
 bool CreateCacheTestFile(const wchar_t* name);
 
 // Deletes all file son the cache.
+bool DeleteCache(const FilePath& path);
+// Deprecated.
 bool DeleteCache(const wchar_t* path);
 
 // Gets the path to the cache test folder.