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/pdf/browser/BUILD.gn b/components/pdf/browser/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..7434a8f4905dd891d1aa4f231605958fd170572d
--- /dev/null
+++ b/components/pdf/browser/BUILD.gn
@@ -0,0 +1,19 @@
+# Copyright 2014 The Chromium Authors. All rights reserved.
+# 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("browser") {
+  sources = [
+    "open_pdf_in_reader_prompt_client.h",
+    "pdf_web_contents_helper.cc",
+    "pdf_web_contents_helper.h",
+    "pdf_web_contents_helper_client.h",
+  ]
+
+  deps = [
+    "//components/pdf/common",
+    "//content/public/browser",
+  ]
+}