Remove dependency from NaCl code on chrome_constants.

chrome/browser/nacl_host/nacl_browser.h

Index: chrome/browser/nacl_host/nacl_browser.h
diff --git a/chrome/browser/nacl_host/nacl_browser.h b/chrome/browser/nacl_host/nacl_browser.h
index e2f041e43e88810aa087b666fd7aeed95776ee25..77bae0fdf97a9e3de7007455b0f77bc5b86f9b66 100644
--- a/chrome/browser/nacl_host/nacl_browser.h
+++ b/chrome/browser/nacl_host/nacl_browser.h
@@ -109,6 +109,11 @@ class NaClBrowser {
   bool QueryKnownToValidate(const std::string& signature, bool off_the_record);
   void SetKnownToValidate(const std::string& signature, bool off_the_record);
   void ClearValidationCache(const base::Closure& callback);
+#if defined(OS_WIN)
+  // Get path to NaCl loader on the filesystem if possible.
+  // |exe_path| does not change if the method fails.
+  bool GetNaCl64ExePath(base::FilePath* exe_path);
+#endif
 
  private:
   friend struct DefaultSingletonTraits<NaClBrowser>;