Support AudioContextOptions latencyHint as double.

third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html

Index: third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html
diff --git a/third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html b/third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html
index fe5e714bec6aa3949121c1b519bbaaa3264209ae..3d44da1bb6544a34895b747eb2c11a450db27ba5 100644
--- a/third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html
+++ b/third_party/WebKit/LayoutTests/webaudio/audiocontextoptions.html
@@ -11,45 +11,77 @@
   <script>
     var context;
     var audit = Audit.createTaskRunner();
+    var defaultLatency;
+    var interactiveLatency;
+    var balancedLatency;
+    var playbackLatency;
 
     // Task: test AudioContextOptions (1).
     audit.defineTask('test-audiocontextoptions-1', function (done) {
-
       // Verify that an AudioContext can be created with default options.
       Should("context = new AudioContext()", function () {
         context = new AudioContext();
       }).notThrow();
 
-      var defaultLatency = context.baseLatency;
+      defaultLatency = context.baseLatency;
       Should("default baseLatency", defaultLatency).beGreaterThan(0);
 
-      // Verify that any double can be passed and that it results in interactive latency
-      Should("context = new AudioContext({'latencyHint': 0.05})", function () {
-        context = new AudioContext({'latencyHint': 0.05});
-      }).notThrow();
-      Should("double-constructor baseLatency", context.baseLatency).beEqualTo(defaultLatency);
-
       // Verify that an AudioContext can be created with the expected latency types.
       Should("context = new AudioContext({'latencyHint': 'interactive'})", function () {
         context = new AudioContext({'latencyHint': 'interactive'});
       }).notThrow();
 
-      var interactiveLatency = context.baseLatency;
+      interactiveLatency = context.baseLatency;
       Should("interactive baseLatency", interactiveLatency).beEqualTo(defaultLatency);
+      context.close();
 
       Should("context = new AudioContext({'latencyHint': 'balanced'})", function () {
         context = new AudioContext({'latencyHint': 'balanced'});
       }).notThrow();
 
-      var balancedLatency = context.baseLatency;
+      balancedLatency = context.baseLatency;
       Should("balanced baseLatency", balancedLatency).beGreaterThanOrEqualTo(interactiveLatency);
+      context.close();
 
       Should("context = new AudioContext({'latencyHint': 'playback'})", function () {
         context = new AudioContext({'latencyHint': 'playback'});
       }).notThrow();
 
-      var playbackLatency = context.baseLatency;
+      playbackLatency = context.baseLatency;
       Should("playback baseLatency", playbackLatency).beGreaterThanOrEqualTo(balancedLatency);
+      context.close();
+
+      done();
+    });
+
+    // Task: test AudioContextOptions (2).

[hongchan, 2017/04/11 17:27:37]

Nit: please wrap by 80 column. I suggest to apply clang-format, unless you want
to learn Google JS style guide. :)

[Andrew MacPherson, 2017/04/12 12:43:41]

Neat, I didn't realize that clang-format could be used with JS code. :) I ran it
on the JS portion of the file after updating to the new audit.js framework, it
actually broke the code in one place (splitting a long quoted string across two
lines) but after fixing that by hand the rest was great.

+    audit.defineTask('test-audiocontextoptions-2', function (done) {
+      // Verify too small exact latency clamped to 'interactive'
+      Should("context = new AudioContext({'latencyHint': interactiveLatency/2})", function () {
+        context = new AudioContext({'latencyHint': interactiveLatency/2});

[hongchan, 2017/04/11 17:27:37]

The try bots do not have an actual audio hardware. Not sure how this latency
calculation will work out when you don't have the audio device?

[Andrew MacPherson, 2017/04/12 12:43:40]

I assumed that the layout_test_content_renderer_client.cc would be used as a
mock here but I think I'm not totally clear on what happens on the trybots. As
long as the trybots are able to create an AudioContext though I believe this
should work correctly.

+      }).notThrow();
+      Should("double-constructor baseLatency small", context.baseLatency).beEqualTo(interactiveLatency);
+      context.close();
+
+      // Verify that exact latency in range works as expected
+      var validLatency = (interactiveLatency + playbackLatency) / 2;
+      Should("context = new AudioContext({'latencyHint': validLatency})", function () {
+        context = new AudioContext({'latencyHint': validLatency});
+      }).notThrow();
+      Should("double-constructor baseLatency inrange 1", context.baseLatency).beGreaterThanOrEqualTo(interactiveLatency);
+      Should("double-constructor baseLatency inrange 2", context.baseLatency).beLessThanOrEqualTo(playbackLatency);
+      context.close();
+
+      // Verify too big exact latency clamped to some value
+      var context1;
+      var context2;
+      Should("creating two high latency contexts", function () {
+        context1 = new AudioContext({'latencyHint': playbackLatency*10});
+        context2 = new AudioContext({'latencyHint': playbackLatency*20});
+      }).notThrow();
+      Should("high latency context baseLatency", context1.baseLatency).beEqualTo(context2.baseLatency);
+      context1.close();
+      context2.close();
 
       // Verify that invalid latencyHint values are rejected.
       Should("context = new AudioContext({'latencyHint': 'foo'})", function () {