Support AudioContextOptions latencyHint as double.

third_party/WebKit/Source/modules/webaudio/AudioContext.cpp

 // Copyright 2015 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.
 
 #include "modules/webaudio/AudioContext.h"
 
 #include "bindings/core/v8/ExceptionMessages.h"
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/ScriptPromiseResolver.h"
 #include "core/dom/DOMException.h"
@@ skipping 36 matching lines @@
         ExceptionMessages::IndexExceedsMaximumBound(
             "number of hardware contexts", g_hardware_context_count,
             kMaxHardwareContexts));
     return nullptr;
   }
 
   WebAudioLatencyHint latency_hint(WebAudioLatencyHint::kCategoryInteractive);
   if (context_options.latencyHint().isAudioContextLatencyCategory()) {
     latency_hint = WebAudioLatencyHint(
         context_options.latencyHint().getAsAudioContextLatencyCategory());
+  } else if (context_options.latencyHint().isDouble()) {
+    // This should be the requested output latency in seconds, without taking
+    // into account double buffering (same as baseLatency).
+    latency_hint =
+        WebAudioLatencyHint(context_options.latencyHint().getAsDouble());
   }
-  // TODO: add support for latencyHint().isDouble()
 
   AudioContext* audio_context = new AudioContext(document, latency_hint);
   audio_context->SuspendIfNeeded();
 
   if (!AudioUtilities::IsValidAudioBufferSampleRate(
           audio_context->sampleRate())) {
     exception_state.ThrowDOMException(
         kNotSupportedError,
         ExceptionMessages::IndexOutsideRange(
             "hardware sample rate", audio_context->sampleRate(),
@@ skipping 188 matching lines @@
   DCHECK(destination());
 
   if (ContextState() == kRunning) {
     destination()->GetAudioDestinationHandler().StopRendering();
     SetContextState(kSuspended);
     GetDeferredTaskHandler().ClearHandlersToBeDeleted();
   }
 }
 
 double AudioContext::baseLatency() const {
-  return FramesPerBuffer() * 2 / static_cast<double>(sampleRate());
+  return FramesPerBuffer() / static_cast<double>(sampleRate());
 }
 
 }  // namespace blink