Remove ContextClient from NavigatorCredentialManager

It's unused.

BUG=610176

Review-Url: https://codereview.chromium.org/2616013002
Cr-Commit-Position: refs/heads/master@{#441892}

third_party/WebKit/Source/modules/credentialmanager/NavigatorCredentials.cpp

@@ -13,7 +13,7 @@
 namespace blink {
 
 NavigatorCredentials::NavigatorCredentials(Navigator& navigator)
-    : ContextClient(navigator.frame()) {}
+    : Supplement<Navigator>(navigator) {}
 
 NavigatorCredentials& NavigatorCredentials::from(Navigator& navigator) {
   NavigatorCredentials* supplement = static_cast<NavigatorCredentials*>(
@@ -34,7 +34,7 @@ CredentialsContainer* NavigatorCredentials::credentials(Navigator& navigator) {
 }
 
 CredentialsContainer* NavigatorCredentials::credentials() {
-  if (!m_credentialsContainer && frame())
+  if (!m_credentialsContainer)
     m_credentialsContainer = CredentialsContainer::create();
   return m_credentialsContainer.get();
 }
@@ -42,7 +42,6 @@ CredentialsContainer* NavigatorCredentials::credentials() {
 DEFINE_TRACE(NavigatorCredentials) {
   visitor->trace(m_credentialsContainer);
   Supplement<Navigator>::trace(visitor);
-  ContextClient::trace(visitor);
 }
 
 }  // namespace blink

third_party/WebKit/Source/modules/credentialmanager/NavigatorCredentials.h

@@ -5,7 +5,6 @@
 #ifndef NavigatorCredentials_h
 #define NavigatorCredentials_h
 
-#include "core/dom/ContextLifecycleObserver.h"
 #include "core/frame/Navigator.h"
 #include "platform/Supplementable.h"
 #include "platform/heap/Handle.h"
@@ -17,8 +16,7 @@ class Navigator;
 
 class NavigatorCredentials final
     : public GarbageCollected<NavigatorCredentials>,
-      public Supplement<Navigator>,
-      public ContextClient {
+      public Supplement<Navigator> {
   USING_GARBAGE_COLLECTED_MIXIN(NavigatorCredentials);
 
  public: