media: Add build flag for CDM host verification

ppapi/features/features.gni

Index: ppapi/features/features.gni
diff --git a/ppapi/features/features.gni b/ppapi/features/features.gni
index 5982e3146d0d31149023c086c1801298d263f922..30f8f05e12e814d10da5f5c1dd57a04d3f5f3f0f 100644
--- a/ppapi/features/features.gni
+++ b/ppapi/features/features.gni
@@ -2,8 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/features.gni")
+import("//third_party/widevine/cdm/widevine.gni")
 
 declare_args() {
   enable_plugins = !is_android && !is_ios && !is_chromecast
@@ -14,3 +16,7 @@ declare_args() {
 # This is available as a buildflag for C++ preprocessor, see
 # //ppapi:features.
 enable_pepper_cdms = enable_plugins && (is_linux || is_mac || is_win)
+
+# Enables host verification for CDMs.
+enable_cdm_host_verification = enable_pepper_cdms && (is_mac || is_win) &&
+                               (is_chrome_branded || enable_widevine)