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

components/BUILD.gn

Index: components/BUILD.gn
diff --git a/components/BUILD.gn b/components/BUILD.gn
index afb2e63ccea2be2b10faece08e3acf7b37c5b847..3f05d349f1d65c1488d9aae54d56a1e05db105bf 100644
--- a/components/BUILD.gn
+++ b/components/BUILD.gn
@@ -2,6 +2,8 @@
 # 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")
+
 # Collection of all components. You wouldn't link to this, but this is rather
 # to reference the files so they can be compiled by the build system.
 group("all_components") {
@@ -56,6 +58,9 @@ group("all_components") {
     "//components/password_manager/content/browser",
     "//components/password_manager/core/browser",
     "//components/password_manager/core/common",
+    "//components/pdf/browser",
+    "//components/pdf/common",
+    "//components/pdf/renderer",
     "//components/plugins/renderer",
     "//components/policy",
     "//components/power",
@@ -105,6 +110,14 @@ group("all_components") {
     deps -= [ "//components/keyed_service/content" ]
   }
 
+  if (!enable_plugins) {
+    deps -= [
+      "//components/pdf/browser",
+      "//components/pdf/common",
+      "//components/pdf/renderer",
+    ]
+  }
+
   if (is_android) {
     deps -= [
       "//components/autofill/content/browser",  # Blocked on content/blink.