[Windows MSVC CFG] Add support for CFG, and enable on chrome.exe & chrome_elf.dll.

build/config/win/BUILD.gn

Index: build/config/win/BUILD.gn
diff --git a/build/config/win/BUILD.gn b/build/config/win/BUILD.gn
index 9b6ac7423f2b9d4d12bdea8302a200507d706e6e..13f52847c71a7f7f21a45edd1ecd3623aae4fbf1 100644
--- a/build/config/win/BUILD.gn
+++ b/build/config/win/BUILD.gn
@@ -264,6 +264,17 @@ config("common_linker_setup") {
   }
 }
 
+# Control Flow Guard (CFG)
+# https://msdn.microsoft.com/en-us/library/windows/desktop/mt637065(v=vs.85).aspx

[scottmg, 2016/10/13 22:21:57]

even nittier; remove the (v=vs8.5) part to make it
"https://msdn.microsoft.com/en-us/library/windows/desktop/mt637065.aspx" so that
it fits in 80col.

[penny, 2016/10/13 23:10:21]

Good one.

+config("win_msvc_cfg") {
+  # /DYNAMICBASE (ASLR) is turned off in debug builds,

[scottmg, 2016/10/13 22:21:57]

nit; rewrap this comment.

[penny, 2016/10/13 23:10:21]

Done.

+  # therefore CFG can’t be turned on either.
+  if (!is_clang && !is_debug) {
+    cflags = [ "/guard:cf" ]
+    ldflags = [ "/guard:cf" ]
+  }
+}
+
 # CRT --------------------------------------------------------------------------
 
 # Configures how the runtime library (CRT) is going to be used.