Report if video capturing meets output protection requirement.

content/renderer/media/secure_display_link_tracker.h

Index: content/renderer/media/secure_display_link_tracker.h
diff --git a/content/renderer/media/secure_display_link_tracker.h b/content/renderer/media/secure_display_link_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..d1772b48f92865d3f01a6443f9962cceef9f3c89
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+++ b/content/renderer/media/secure_display_link_tracker.h
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+// Copyright 2016 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.
+
+#ifndef CONTENT_RENDERER_MEDIA_SECURE_DISPLAY_LINK_TRACKER_H_
+#define CONTENT_RENDERER_MEDIA_SECURE_DISPLAY_LINK_TRACKER_H_
+
+#include <vector>
+
+// Tracks all connected links (video sinks / tracks), and reports if they are
+// all secure for video capturing.
+template <typename T>
+class SecureDisplayLinkTracker {
+ public:
+  SecureDisplayLinkTracker() {}
+  ~SecureDisplayLinkTracker() {}
+
+  void Add(T* link, bool is_link_secure);
+  void Remove(T* link);
+  void Update(T* link, bool is_link_secure);
+  bool is_capturing_secure() const { return insecure_links_.empty(); }
+
+ private:
+  // Record every insecure links.
+  std::vector<T*> insecure_links_;
+
+  DISALLOW_COPY_AND_ASSIGN(SecureDisplayLinkTracker);
+};
+
+template <typename T>
+void SecureDisplayLinkTracker<T>::Add(T* link, bool is_link_secure) {
+  DCHECK(std::find(insecure_links_.begin(), insecure_links_.end(), link) ==
+         insecure_links_.end());
+
+  if (!is_link_secure)
+    insecure_links_.push_back(link);
+}
+
+template <typename T>
+void SecureDisplayLinkTracker<T>::Remove(T* link) {
+  auto it = std::find(insecure_links_.begin(), insecure_links_.end(), link);
+  if (it != insecure_links_.end())
+    insecure_links_.erase(it);
+}
+
+template <typename T>
+void SecureDisplayLinkTracker<T>::Update(T* link, bool is_link_secure) {
+  auto it = std::find(insecure_links_.begin(), insecure_links_.end(), link);
+  if (it != insecure_links_.end()) {
+    if (is_link_secure)
+      insecure_links_.erase(it);
+    return;
+  }
+  Add(link, is_link_secure);
+}
+
+#endif  // CONTENT_RENDERER_MEDIA_SECURE_DISPLAY_LINK_TRACKER_H_