Revert of Move ENABLE_PEPPER_CDMS to a buildflag header.

third_party/widevine/cdm/BUILD.gn

Index: third_party/widevine/cdm/BUILD.gn
diff --git a/third_party/widevine/cdm/BUILD.gn b/third_party/widevine/cdm/BUILD.gn
index 8b40b1ab1e7ac238cb695cb177fae873e7cf9eb3..a6c45e06cf636a60696f854523f1e0d72e49d51f 100644
--- a/third_party/widevine/cdm/BUILD.gn
+++ b/third_party/widevine/cdm/BUILD.gn
@@ -7,7 +7,6 @@
 import("//chrome/process_version_rc_template.gni")
 import("//media/cdm/ppapi/cdm_paths.gni")
 import("//media/cdm/ppapi/ppapi_cdm_adapter.gni")
-import("//ppapi/features/features.gni")
 import("//third_party/widevine/cdm/widevine.gni")
 
 widevine_arch = current_cpu
@@ -53,7 +52,6 @@
 }
 
 copy("version_h") {
-  visibility = [ ":*" ]  # Depend on ":headers" instead.
   sources = [
     widevine_cdm_version_h_file,
   ]
@@ -63,17 +61,6 @@
   # widevine_cdm_version.h in this directory to avoid conflicts.
   outputs = [
     "$root_gen_dir/widevine_cdm_version.h",
-  ]
-}
-
-source_set("headers") {
-  public = [
-    "widevine_cdm_common.h",
-  ]
-
-  public_deps = [
-    ":version_h",  # Forward permission to use version header.
-    "//ppapi/features",
   ]
 }