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..260f580444d6937b5114b1686a9f79c190299594
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+++ b/third_party/WebKit/public/platform/WebAudioLatencyHint.h
@@ -0,0 +1,39 @@
+// 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 {

[Raymond Toy, 2016/12/08 17:14:38]

I assume this class will also be used to hold the float latency value.

Would it be hard to make this include the necessary information.  I think it
would be ideal if we supported the necessary slots and methods to expose this,
even if we don't support float latency right now.

I'm just trying to avoid a future big change if this class is not structured
correctly for a float latency.

[Andrew MacPherson, 2016/12/09 12:34:14]

No problem, I've just added a new Category, double m_seconds member, constructor
and getter method. I also had to add this new Category to a switch statement in
content/renderer, hopefully this doesn't affect olka@'s lgtm. Does that work?

+ public:
+  enum Category { CategoryInteractive, CategoryBalanced, CategoryPlayback };
+
+  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 {
+      NOTREACHED();
+      m_category = CategoryInteractive;
+    }
+  }
+
+  explicit WebAudioLatencyHint(Category category) : m_category(category) {}
+
+  Category category() const { return m_category; }
+
+ private:
+  Category m_category;
+};
+
+}  // namespace blink
+
+#endif