Extend ServletModule instead of HttpPluginModule

As described in I3b89150d1.

Change-Id: Ic91ce95719c6bccc73cc29a2139a2274f20d1939

src/main/java/com/googlesource/gerrit/plugins/oauth/HttpModule.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/oauth/HttpModule.java b/src/main/java/com/googlesource/gerrit/plugins/oauth/HttpModule.java
index d51d918..5348c00 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/oauth/HttpModule.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/oauth/HttpModule.java
@@ -17,12 +17,12 @@
 import com.google.gerrit.extensions.annotations.Exports;
 import com.google.gerrit.extensions.annotations.PluginName;
 import com.google.gerrit.extensions.auth.oauth.OAuthServiceProvider;
-import com.google.gerrit.httpd.plugins.HttpPluginModule;
 import com.google.gerrit.server.config.PluginConfig;
 import com.google.gerrit.server.config.PluginConfigFactory;
 import com.google.inject.Inject;
+import com.google.inject.servlet.ServletModule;
 
-class HttpModule extends HttpPluginModule {
+class HttpModule extends ServletModule {
 
   private final PluginConfigFactory cfgFactory;
   private final String pluginName;