pdf: Create a separate component for using the pdf pepper plugin.

components/pdf/common/BUILD.gn

Index: components/pdf/common/BUILD.gn
diff --git a/components/cdm/common/BUILD.gn b/components/pdf/common/BUILD.gn
similarity index 67%
copy from components/cdm/common/BUILD.gn
copy to components/pdf/common/BUILD.gn
index 7af38692c592d082a2b4a2963c2c27c61ae160a9..adff35e0ba6aa6d004194a4d10a576fb81e840bc 100644
--- a/components/cdm/common/BUILD.gn
+++ b/components/pdf/common/BUILD.gn
@@ -2,16 +2,19 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")
+
 static_library("common") {
   sources = [
-    "cdm_message_generator.cc",
-    "cdm_message_generator.h",
-    "cdm_messages_android.h",
+    "pdf_message_generator.cc",
+    "pdf_message_generator.h",
+    "pdf_messages.h",
   ]
 
   deps = [
     "//base",
     "//content/public/common",
     "//ipc",
+    "//url",
   ]
 }