Support for AudioContextOptions latencyHint.

third_party/WebKit/public/platform/WebAudioLatencyHint.h

Index: third_party/WebKit/public/platform/WebAudioLatencyHint.h
diff --git a/third_party/WebKit/public/platform/WebAudioLatencyHint.h b/third_party/WebKit/public/platform/WebAudioLatencyHint.h
new file mode 100644
index 0000000000000000000000000000000000000000..5bc386daf6548806f65a67c02743ce12e298ffa6
--- /dev/null
+++ b/third_party/WebKit/public/platform/WebAudioLatencyHint.h
@@ -0,0 +1,49 @@
+// 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 WebAudioLatencyHint_h
+#define WebAudioLatencyHint_h
+
+#include "WebString.h"
+
+namespace blink {
+
+class WebAudioLatencyHint {
+ public:
+  enum Category {

[Raymond Toy, 2016/12/13 15:53:11]

Category seems a bit terse.  Maybe AudioLatencyCategory or even
AudioContextLatencyCategory (if this doesn't collide with  anything.

[Andrew MacPherson, 2016/12/14 09:07:20]

Done, with AudioContextLatencyCategory.

+    CategoryInteractive,
+    CategoryBalanced,
+    CategoryPlayback,
+    CategoryExact
+  };

[Raymond Toy, 2016/12/13 15:53:11]

https://www.chromium.org/blink/coding-style, item 12 says to use kCamelCase for
enums.

[Andrew MacPherson, 2016/12/14 09:07:20]

Done.

+
+  explicit WebAudioLatencyHint(WebString category) {
+    if (category == "interactive") {
+      m_category = CategoryInteractive;
+    } else if (category == "balanced") {
+      m_category = CategoryBalanced;
+    } else if (category == "playback") {
+      m_category = CategoryPlayback;
+    } else {

[Raymond Toy, 2016/12/13 15:53:11]

I think you need a case for category == CategoryExact.

[Andrew MacPherson, 2016/12/14 09:07:20]

Should it be possible to create a WebAudioLatencyHint with CategoryExact by
passing a String into the constructor? Right now the IDL prevents passing
anything but these three strings.

[Raymond Toy, 2016/12/14 18:23:32]

Sorry, you're right. It shouldn't be possible, and you have tests for this
already.

+      NOTREACHED();
+      m_category = CategoryInteractive;
+    }
+  }
+
+  explicit WebAudioLatencyHint(Category category)
+      : m_category(category), m_seconds(0) {}
+  explicit WebAudioLatencyHint(double seconds)
+      : m_category(CategoryExact), m_seconds(seconds) {}
+
+  Category category() const { return m_category; }
+  double seconds() const { return m_seconds; }

[Raymond Toy, 2016/12/13 15:53:11]

Should there be asserts here so that you only ask for seconds() when the
category is CategoryExact?

[Andrew MacPherson, 2016/12/14 09:07:20]

Done.

+
+ private:
+  Category m_category;
+  double m_seconds;
+};
+
+}  // namespace blink
+
+#endif