Support for AudioContextOptions latencyHint.

third_party/WebKit/public/platform/WebAudioLatencyHint.h

+// 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.
+
+#ifndef WebAudioLatencyHint_h
+#define WebAudioLatencyHint_h
+
+#include "public/platform/WebString.h"
+
+namespace blink {
+
+class WebAudioLatencyHint {
+ public:
+  enum AudioContextLatencyCategory {
+    kCategoryInteractive,
+    kCategoryBalanced,
+    kCategoryPlayback,
+    kCategoryExact
+  };
+
+  explicit WebAudioLatencyHint(const WebString& category) {
+    if (category == "interactive") {
+      m_category = kCategoryInteractive;
+    } else if (category == "balanced") {
+      m_category = kCategoryBalanced;
+    } else if (category == "playback") {
+      m_category = kCategoryPlayback;
+    } else {
+      NOTREACHED();
+      m_category = kCategoryInteractive;
+    }
+  }
+
+  explicit WebAudioLatencyHint(AudioContextLatencyCategory category)
+      : m_category(category), m_seconds(0) {}
+  explicit WebAudioLatencyHint(double seconds)
+      : m_category(kCategoryExact), m_seconds(seconds) {}
+
+  AudioContextLatencyCategory category() const { return m_category; }
+  double seconds() const {
+    DCHECK_EQ(m_category, kCategoryExact);
+    return m_seconds;
+  }
+
+ private:
+  AudioContextLatencyCategory m_category;
+  double m_seconds;
+};
+
+}  // namespace blink
+
+#endif