Replace c/b/nss_context by a KeyedService.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 6c76a37a55e4a300b9f63e91b703ec8509c6d1d3..de71afb2bb423c41f22bbd0a92b9adb59dcd8fda 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1775,10 +1775,8 @@
     'chrome_browser_nss_sources': [
       'browser/certificate_manager_model.cc',
       'browser/certificate_manager_model.h',
-      'browser/net/nss_context.cc',
-      'browser/net/nss_context.h',
-      'browser/net/nss_context_chromeos.cc',
-      'browser/net/nss_context_linux.cc',
+      'browser/net/cert_database_service_factory.cc',
+      'browser/net/cert_database_service_factory.h',
       'third_party/mozilla_security_manager/nsNSSCertHelper.cpp',
       'third_party/mozilla_security_manager/nsNSSCertHelper.h',
       'third_party/mozilla_security_manager/nsNSSCertificate.cpp',
@@ -3189,12 +3187,8 @@
         }],
         ['use_nss==1', {
           'sources': [ '<@(chrome_browser_nss_sources)' ],
-          'conditions': [
-            ['chromeos==1', {
-               'sources!': [ 'browser/net/nss_context_linux.cc' ],
-              }, { # chromeos==0
-               'sources!': [ 'browser/net/nss_context_chromeos.cc' ],
-              }],
+          'dependencies': [
+            '../components/components.gyp:cert_database',
           ],
         }],
         ['notifications==1', {