Add a whitelist for the new binary download protection.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index fb7fb33f3ea4b7ea572eca769f2088160cf15b15..2cea36ad02a45248556a82a60d82f86efda64b2b 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -446,6 +446,10 @@ const char kEnableFastback[]                = "enable-fastback";
 // testing, for example page cycler and layout tests.  See bug 1157243.
 const char kEnableFileCookies[]             = "enable-file-cookies";
 
+// Enable improved SafeBrowsing download protection.
+const char kEnableImprovedDownloadProtection[] =
+    "enable-improved-download-protection";
+
 // Enable the in-browser thumbnailing, which is more efficient than the
 // in-renderer thumbnailing, as we can use more information to determine
 // if we need to update thumbnails.