Make compiles fail when __DATE__, __TIME__, or __TIMESTAMP_ are used.

build/config/compiler/BUILD.gn

Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index 5e6d53095474bd9dcaaedf8b2d818170ffb79ed7..1a3908c4ad5ec366f6f2edae4ab1e7b3be884b0e 100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -964,6 +964,14 @@ config("default_warnings") {
     }
   }
 
+  if (!is_nacl && (!is_win || is_clang)) {
+    # Disable __DATE__ and __TIME__ to help make builds deterministic.
+    # Determinism is important, so we should fix compile failures rather
+    # than remove this flag (this is also why this is in :common_warnings
+    # rather than :chromium_code).
+    cflags += [ "-Wdate-time" ]
+  }
+
   # Common Clang and GCC warning setup.
   if (!is_win || is_clang) {
     cflags += [