Move ENABLE_PEPPER_CDMS to a buildflag header.

content/renderer/BUILD.gn

Index: content/renderer/BUILD.gn
diff --git a/content/renderer/BUILD.gn b/content/renderer/BUILD.gn
index d97a89ff80a0af480e70260a89aaa0b8b9c2ed6a..6f90979b94210a61e31ef299ad1c6f3639933c03 100644
--- a/content/renderer/BUILD.gn
+++ b/content/renderer/BUILD.gn
@@ -5,6 +5,7 @@
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//media/media_options.gni")
+import("//ppapi/features/features.gni")
 import("//third_party/webrtc/build/webrtc.gni")
 import("//tools/ipc_fuzzer/ipc_fuzzer.gni")
 
@@ -439,6 +440,7 @@ target(link_target_type, "renderer") {
     "//mojo/public/cpp/bindings",
     "//mojo/public/js",
     "//net",
+    "//ppapi/features",
     "//sandbox",
     "//services/shell/public/cpp",
     "//services/shell/public/interfaces",
@@ -450,7 +452,7 @@ target(link_target_type, "renderer") {
     "//third_party/icu",
     "//third_party/libjingle",
     "//third_party/libyuv",
-    "//third_party/widevine/cdm:version_h",
+    "//third_party/widevine/cdm:headers",
     "//ui/accessibility",
     "//ui/base",
     "//ui/base/ime",