Implement some WiFi Display elementary stream descriptors.

extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_descriptor.h

Index: extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_descriptor.h
diff --git a/extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_descriptor.h b/extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_descriptor.h
new file mode 100644
index 0000000000000000000000000000000000000000..9cc3bcf2464683db8ac4f24c0b3436bee40a389b
--- /dev/null
+++ b/extensions/renderer/api/display_source/wifi_display/wifi_display_elementary_stream_descriptor.h
@@ -0,0 +1,122 @@
+// 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 EXTENSIONS_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_ELEMENTARY_STREAM_DESCRIPTOR_H_
+#define EXTENSIONS_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_ELEMENTARY_STREAM_DESCRIPTOR_H_
+
+#include <stdint.h>
+#include <type_traits>
+
+#include "base/memory/scoped_ptr.h"
+
+namespace extensions {
+
+// WiFi Display elementary stream descriptors are used for passing descriptive
+// information about elementary streams to WiFiDisplayTransportStreamPacketizer
+// which then packetizes that information so that it can be passed to a remote
+// sink.
+class WiFiDisplayElementaryStreamDescriptor {
+ public:
+  enum { kHeaderSize = 2u };
+
+  enum DescriptorTag : uint8_t {
+    DESCRIPTOR_TAG_AVC_VIDEO = 0x28u,
+    DESCRIPTOR_TAG_AVC_TIMING_AND_HRD = 0x2A,
+    DESCRIPTOR_TAG_LPCM_AUDIO_STREAM = 0x83u,
+  };
+
+  // Make Google Test to treat this class as a container.

[asargent_no_longer_on_chrome, 2016/03/18 18:24:47]

grammar nit: "Make Google Test to treat" should be just "Make Google Test treat"

+  using const_iterator = const uint8_t*;
+  using iterator = const uint8_t*;
+
+  WiFiDisplayElementaryStreamDescriptor(
+      const WiFiDisplayElementaryStreamDescriptor&);
+  WiFiDisplayElementaryStreamDescriptor(
+      WiFiDisplayElementaryStreamDescriptor&&);
+  ~WiFiDisplayElementaryStreamDescriptor();
+
+  WiFiDisplayElementaryStreamDescriptor& operator=(
+      WiFiDisplayElementaryStreamDescriptor&&);
+
+  const uint8_t* begin() const { return data(); }
+  const uint8_t* data() const;
+  bool empty() const { return !data_; }
+  const uint8_t* end() const { return data() + size(); }
+  size_t size() const;
+
+  DescriptorTag tag() const { return static_cast<DescriptorTag>(data()[0]); }
+  uint8_t length() const { return data()[1]; }
+
+  // AVC (Advanced Video Coding) timing and HRD (Hypothetical Reference
+  // Decoder) descriptor provides timing and HRD parameters for a video stream.
+  struct AVCTimingAndHRD {
+    static WiFiDisplayElementaryStreamDescriptor Create();
+  };
+
+  // AVC (Advanced Video Coding) video descriptor provides basic coding
+  // parameters for a video stream.
+  struct AVCVideo {
+    static WiFiDisplayElementaryStreamDescriptor Create(
+        uint8_t profile_idc,
+        bool constraint_set0_flag,
+        bool constraint_set1_flag,
+        bool constraint_set2_flag,
+        uint8_t avc_compatible_flags,
+        uint8_t level_idc,
+        bool avc_still_present);
+  };
+
+  class LPCMAudioStream;
+
+ protected:
+  WiFiDisplayElementaryStreamDescriptor(DescriptorTag tag, uint8_t length);
+
+  uint8_t* data();
+  const uint8_t* private_data() const { return data() + kHeaderSize; }
+  uint8_t* private_data() { return data() + kHeaderSize; }
+
+ private:
+  scoped_ptr<uint8_t[]> data_;
+};
+
+// LPCM (Linear pulse-code modulation) audio stream descriptor provides basic
+// coding parameters for a private WiFi Display LPCM audio stream.
+class WiFiDisplayElementaryStreamDescriptor::LPCMAudioStream
+    : public WiFiDisplayElementaryStreamDescriptor {
+ public:
+  enum { kTag = DESCRIPTOR_TAG_LPCM_AUDIO_STREAM };
+  enum BitsPerSample : uint8_t { BITS_PER_SAMPLE_16 = 0u };
+  enum NumberOfChannels : uint8_t {
+    NUMBER_OF_CHANNELS_DUAL_MONO = 0u,
+    NUMBER_OF_CHANNELS_STEREO = 1u
+  };
+  enum SamplingFrequency : uint8_t {
+    SAMPLING_FREQUENCY_44_1K = 1u,
+    SAMPLING_FREQUENCY_48K = 2u
+  };
+
+  static WiFiDisplayElementaryStreamDescriptor Create(
+      SamplingFrequency sampling_frequency,
+      BitsPerSample bits_per_sample,
+      bool emphasis_flag,
+      NumberOfChannels number_of_channels);
+
+  BitsPerSample bits_per_sample() const;
+  bool emphasis_flag() const;
+  NumberOfChannels number_of_channels() const;
+  SamplingFrequency sampling_frequency() const;
+};
+
+// Subclasses of WiFiDisplayElementaryStreamDescriptor MUST NOT define new
+// member variables but only new non-virtual member functions which parse
+// the inherited data. This allows WiFiDisplayElementaryStreamDescriptor
+// pointers to be cast to subclass pointers.
+static_assert(
+    std::is_standard_layout<
+        WiFiDisplayElementaryStreamDescriptor::LPCMAudioStream>::value,
+    "Forbidden memory layout for an elementary stream descriptor");
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_API_DISPLAY_SOURCE_WIFI_DISPLAY_WIFI_DISPLAY_ELEMENTARY_STREAM_DESCRIPTOR_H_