media config: expand is_encrypted to a struct.

media/base/encryption_scheme.cc

+// Copyright 2015 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 "media/base/encryption_scheme.h"
+
+#include "base/logging.h"

[ddorwin, 2015/12/10 18:36:01]

I don't think this is currently used, but it may be after addressing one of my
comments.

[dougsteed, 2016/03/02 18:07:52]

Done.

+
+namespace media {
+
+EncryptionScheme::EncryptionScheme()
+    : is_encrypted_(false), mode_(kCipherModeAesCtr), pattern_() {}

[ddorwin, 2015/12/10 18:36:00]

Why not kCipherModeUnknown?

[dougsteed, 2015/12/14 21:19:01]

Up until now, AES-CTR is the default (at least for CENC), and I don't know all
the places where that is assumed. So I think it is safer to preserve a form of
backwards-compatibility where AES-CTR is the default. However, in those places
where the code is really just using an is_encrypted boolean, then it doesn't
care about the mode anyway, and will never ask for it.

+
+EncryptionScheme::EncryptionScheme(bool is_encrypted)
+    : is_encrypted_(is_encrypted), mode_(kCipherModeAesCtr), pattern_() {}
+
+EncryptionScheme::EncryptionScheme(CipherMode mode)
+    : is_encrypted_(true), mode_(mode), pattern_() {}
+
+EncryptionScheme::EncryptionScheme(CipherMode mode, const PatternSpec& pattern)
+    : is_encrypted_(true), mode_(mode), pattern_(pattern) {}
+
+EncryptionScheme::EncryptionScheme(bool is_encrypted,
+                                   CipherMode mode,
+                                   const PatternSpec& pattern)
+    : is_encrypted_(is_encrypted), mode_(mode), pattern_(pattern) {}
+
+void EncryptionScheme::Initialize(bool is_encrypted,
+                                  CipherMode mode,
+                                  const PatternSpec& pattern) {
+  is_encrypted_ = is_encrypted;
+  mode_ = mode;
+  pattern_ = pattern;
+}
+
+bool EncryptionScheme::Matches(const EncryptionScheme& other) const {
+  return is_encrypted_ == other.is_encrypted_ && mode_ == other.mode_ &&
+         pattern_.Matches(other.pattern_);
+}
+
+EncryptionScheme::PatternSpec::PatternSpec()

[ddorwin, 2015/12/10 18:36:00]

nit: Define in the same order as declared. This internal class was before the
constructors.

[dougsteed, 2015/12/14 21:19:01]

Done.

+    : encrypt_blocks_(0), skip_blocks_(0) {}
+
+EncryptionScheme::PatternSpec::PatternSpec(uint32_t encrypt_blocks,
+                                           uint32_t skip_blocks)
+    : encrypt_blocks_(encrypt_blocks), skip_blocks_(skip_blocks) {}
+
+void EncryptionScheme::PatternSpec::Initialize(uint32_t encrypt_blocks,
+                                               uint32_t skip_blocks) {
+  encrypt_blocks_ = encrypt_blocks;
+  skip_blocks_ = skip_blocks;
+}
+
+bool EncryptionScheme::PatternSpec::Matches(const PatternSpec& other) const {
+  return encrypt_blocks_ == other.encrypt_blocks() &&
+         skip_blocks_ == other.skip_blocks();
+}
+
+}  // namespace media