Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend

apps/shell/browser/shell_extensions_browser_client.cc

Index: apps/shell/browser/shell_extensions_browser_client.cc
diff --git a/apps/shell/browser/shell_extensions_browser_client.cc b/apps/shell/browser/shell_extensions_browser_client.cc
index 2c9a56f87c2c26cf49f8f8f50748718980aed987..8f896334f39eba37ecadab8f0b6e4cc1012fb201 100644
--- a/apps/shell/browser/shell_extensions_browser_client.cc
+++ b/apps/shell/browser/shell_extensions_browser_client.cc
@@ -11,6 +11,7 @@
 #include "base/prefs/testing_pref_store.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 #include "components/user_prefs/user_prefs.h"
+#include "extensions/browser/api/extensions_api_client.h"
 #include "extensions/browser/app_sorting.h"
 #include "extensions/browser/extension_prefs.h"
 
@@ -26,10 +27,11 @@ void RegisterPrefs(user_prefs::PrefRegistrySyncable* registry) {
 
 }  // namespace
 
-
 ShellExtensionsBrowserClient::ShellExtensionsBrowserClient(
     BrowserContext* context)
-    : browser_context_(context) {
+    : browser_context_(context), api_client_(new ExtensionsApiClient) {
+  ExtensionsApiClient::Set(api_client_.get());
+
   // Set up the preferences service.
   base::PrefServiceFactory factory;
   factory.set_user_prefs(new TestingPrefStore);
@@ -45,7 +47,9 @@ ShellExtensionsBrowserClient::ShellExtensionsBrowserClient(
   user_prefs::UserPrefs::Set(browser_context_, prefs_.get());
 }
 
-ShellExtensionsBrowserClient::~ShellExtensionsBrowserClient() {}
+ShellExtensionsBrowserClient::~ShellExtensionsBrowserClient() {
+  ExtensionsApiClient::Set(NULL);
+}
 
 bool ShellExtensionsBrowserClient::IsShuttingDown() {
   return false;