Populate download_file_types proto and filter it for each platform

chrome/common/safe_browsing/download_protection_util.cc

Index: chrome/common/safe_browsing/download_protection_util.cc
diff --git a/chrome/common/safe_browsing/download_protection_util.cc b/chrome/common/safe_browsing/download_protection_util.cc
index 381ae51dd8d8414d643fece2889cc9f8990b908f..d6b35ce4510dcb83c6cc6e493721efd7a03b5e65 100644
--- a/chrome/common/safe_browsing/download_protection_util.cc
+++ b/chrome/common/safe_browsing/download_protection_util.cc
@@ -282,10 +282,15 @@ enum SBClientDownloadExtensions {
   EXTENSION_NDIF,
   EXTENSION_UDIF,
   EXTENSION_TOAST,
+
   // New values go above this one.
   EXTENSION_MAX
 };
 
+static_assert(EXTENSION_TOAST + 1 == EXTENSION_MAX,
+              "You must add new types to download_file_types.asciipb as "
+              "well.");
+
 struct SafeBrowsingFiletype {
   const base::FilePath::CharType* const extension;
   int uma_value;