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

components/pdf/browser/BUILD.gn

Index: components/pdf/browser/BUILD.gn
diff --git a/components/cdm/browser/BUILD.gn b/components/pdf/browser/BUILD.gn
similarity index 51%
copy from components/cdm/browser/BUILD.gn
copy to components/pdf/browser/BUILD.gn
index e18b67035e55756ee7f08d3048949c8f8a7feb7b..b0a10e0dfbbf65bf23a0644a9681b1835c6e0d90 100644
--- a/components/cdm/browser/BUILD.gn
+++ b/components/pdf/browser/BUILD.gn
@@ -2,17 +2,18 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("browser") {
+import("//build/config/features.gni")
+
+static_library("browser") {
   sources = [
-    "cdm_message_filter_android.cc",
-    "cdm_message_filter_android.h",
+    "open_pdf_in_reader_prompt_client.h",
+    "pdf_tab_helper.cc",
+    "pdf_tab_helper.h",
+    "pdf_tab_helper_client.h",
   ]
 
   deps = [
-    "//base",
-    "//components/cdm/common",
+    "//components/pdf/common",
     "//content/public/browser",
-    "//content/public/common",
-    "//media",
   ]
 }