[subresource_filter] Add observer interface for page activation

components/subresource_filter/content/browser/subresource_filter_observer_manager.cc

Index: components/subresource_filter/content/browser/subresource_filter_observer_manager.cc
diff --git a/components/subresource_filter/content/browser/subresource_filter_observer_manager.cc b/components/subresource_filter/content/browser/subresource_filter_observer_manager.cc
new file mode 100644
index 0000000000000000000000000000000000000000..f3b891c7aeef168ad2e10398a2edf4e1d13672ec
--- /dev/null
+++ b/components/subresource_filter/content/browser/subresource_filter_observer_manager.cc
@@ -0,0 +1,42 @@
+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/subresource_filter/content/browser/subresource_filter_observer_manager.h"
+
+#include "components/subresource_filter/core/common/activation_state.h"
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(
+    subresource_filter::SubresourceFilterObserverManager);
+
+namespace subresource_filter {
+
+SubresourceFilterObserverManager::SubresourceFilterObserverManager(
+    content::WebContents* web_contents) {}
+
+SubresourceFilterObserverManager::~SubresourceFilterObserverManager() {
+  for (auto& observer : observers_)
+    observer.OnSubresourceFilterGoingAway();
+}
+
+void SubresourceFilterObserverManager::AddObserver(
+    SubresourceFilterObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void SubresourceFilterObserverManager::RemoveObserver(
+    SubresourceFilterObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+void SubresourceFilterObserverManager::NotifyPageActivationComputed(
+    content::NavigationHandle* navigation_handle,
+    ActivationDecision activation_decision,
+    const ActivationState& activation_state) {
+  for (auto& observer : observers_) {
+    observer.OnPageActivationComputed(navigation_handle, activation_decision,
+                                      activation_state);
+  }
+}
+
+}  // namespace subresource_filter