[Offline Pages] Add a GCMAppHandler for offline page prefetch.

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 42efbabfc2b45dfa68e0deae911cdd00f8f695fc..79cfe09fd3178b1ca4b63ddca61d349769331066 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -9,6 +9,7 @@ import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 import("//chrome/chrome_repack_locales.gni")
+import("//components/offline_pages/features/features.gni")
 import("//components/os_crypt/features.gni")
 import("//components/spellcheck/spellcheck_build_features.gni")
 import("//extensions/features/features.gni")
@@ -3428,6 +3429,7 @@ test("unit_tests") {
       "../browser/android/search_geolocation/search_geolocation_service_unittest.cc",
       "../browser/autofill/autofill_credit_card_filling_infobar_delegate_mobile_unittest.cc",
       "../browser/autofill/autofill_save_card_infobar_delegate_mobile_unittest.cc",
+      "../browser/offline_pages/prefetch/suggested_articles_observer_unittest.cc",

[dewittj, 2017/05/16 17:56:44]

note: I put this in |is_android| because tests have not been ported to use
|enable_offline_pages|

       "../browser/password_manager/account_chooser_dialog_android_unittest.cc",
       "../browser/password_manager/auto_signin_first_run_dialog_android_unittest.cc",
       "../browser/password_manager/save_password_infobar_delegate_android_unittest.cc",