Report if video capturing meets output protection requirement.

content/renderer/media/capturing_link_secure_tracker.h

Index: content/renderer/media/capturing_link_secure_tracker.h
diff --git a/content/renderer/media/capturing_link_secure_tracker.h b/content/renderer/media/capturing_link_secure_tracker.h
new file mode 100644
index 0000000000000000000000000000000000000000..cfcda65e6270ebbeb39c935c13f15637c948ecec
--- /dev/null
+++ b/content/renderer/media/capturing_link_secure_tracker.h
@@ -0,0 +1,82 @@
+// 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_CAPTURING_LINK_SECURT_TRACKER_H_

[miu, 2016/04/26 01:25:13]

s/SECURT/SECURE/

[xjz, 2016/04/29 00:11:42]

Done. 

+#define CONTENT_RENDERER_MEDIA_CAPTURING_LINK_SECURT_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 CapturingLinkSecureTracker {

[miu, 2016/04/26 01:25:14]

Suggestion: Since this is tracking whether downstream display of the video is
secure, consider naming this something like SecureDisplayLinkTracker.

[xjz, 2016/04/29 00:11:42]

Done.

+ public:
+  CapturingLinkSecureTracker() : is_capturing_secure_(true) {}
+  ~CapturingLinkSecureTracker() { DCHECK(links_secure_status_.empty()); }
+
+  void AddLinkSecure(T* link, bool is_link_secure);

[miu, 2016/04/26 01:25:14]

naming nit: How about just Add(), Remove(), and Update()?

[xjz, 2016/04/29 00:11:42]

Done.

+  void RemoveLinkSecure(T* link);
+  void UpdateLinkSecure(T* link, bool is_link_secure);
+  bool is_capturing_secure() { return is_capturing_secure_; }
+
+ private:
+  // This is true only if all connected links are reported secure.
+  bool is_capturing_secure_;
+
+  std::vector<std::pair<T*, bool>> links_secure_status_;

[miu, 2016/04/26 01:25:14]

Idea: What if this class just maintained a vector of *only* the insecure links? 
Then, you don't need the code to re-compute the overall secure status in the
Add/Remove/Update() methods.  Also, is_capturing_secure() then becomes:

  bool is_capturing_secure() const { return insecure_links_.empty(); }

[xjz, 2016/04/29 00:11:42]

Done. Smart idea! Saves many lines of codes and computing time. :-)

+};
+
+template <typename T>
+void CapturingLinkSecureTracker<T>::AddLinkSecure(T* link,
+                                                  bool is_link_secure) {
+  links_secure_status_.push_back(std::make_pair(link, is_link_secure));
+  is_capturing_secure_ &= is_link_secure;
+}
+
+template <typename T>
+void CapturingLinkSecureTracker<T>::RemoveLinkSecure(T* link) {
+  bool is_link_secure = true;
+  for (auto it = links_secure_status_.begin(); it != links_secure_status_.end();
+       ++it) {
+    if (it->first == link) {
+      is_link_secure = it->second;
+      links_secure_status_.erase(it);
+      break;
+    }
+  }
+  if (is_link_secure)
+    return;
+
+  DCHECK(!is_capturing_secure_);
+  // |is_track_secure_| needs to be updated as the removed link is insecure.
+  is_capturing_secure_ = true;
+  for (auto it = links_secure_status_.begin(); it != links_secure_status_.end();
+       ++it)
+    is_capturing_secure_ &= it->second;
+}
+
+template <typename T>
+void CapturingLinkSecureTracker<T>::UpdateLinkSecure(T* link,
+                                                     bool is_link_secure) {
+  for (auto it = links_secure_status_.begin(); it != links_secure_status_.end();
+       ++it) {
+    if (it->first == link) {
+      if (it->second == is_link_secure)
+        return;
+      it->second = is_link_secure;
+      break;
+    }
+  }
+  if (!is_link_secure) {
+    is_capturing_secure_ = false;
+    return;
+  }
+
+  is_capturing_secure_ = true;
+  for (auto it = links_secure_status_.begin(); it != links_secure_status_.end();
+       ++it)
+    is_capturing_secure_ &= it->second;
+}
+
+#endif  // CONTENT_RENDERER_MEDIA_CAPTURING_LINK_SECURT_TRACKER_H_