Fix for AudioContext 'playback' latency on Android

Creating an AudioContext with a latencyHint of 'playback' on some
Android devices could cause glitching as the context was created
with an audio buffer size less than the hardware buffer size.

BUG=745960

Change-Id: I1db4efe934f427c878ad30bfb3507c535383b82d
Reviewed-on: https://chromium-review.googlesource.com/579068Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Raymond Toy <rtoy@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Andrew MacPherson <andrew.macpherson@soundtrap.com>
Cr-Commit-Position: refs/heads/master@{#491308}

content/renderer/media/renderer_webaudiodevice_impl.cc

@@ -61,7 +61,7 @@ int GetOutputBufferSize(const blink::WebAudioLatencyHint& latency_hint,
       break;
     case media::AudioLatency::LATENCY_PLAYBACK:
       return media::AudioLatency::GetHighLatencyBufferSize(
-          hardware_params.sample_rate(), 0);
+          hardware_params.sample_rate(), hardware_params.frames_per_buffer());
       break;
     case media::AudioLatency::LATENCY_EXACT_MS:
       return media::AudioLatency::GetExactBufferSize(

content/renderer/media/renderer_webaudiodevice_impl_unittest.cc

@@ -193,8 +193,8 @@ TEST_F(RendererWebAudioDeviceImplTest, TestLatencyHintValues) {
 
   blink::WebAudioLatencyHint playbackLatencyHint(
       blink::WebAudioLatencyHint::kCategoryPlayback);
-  int playbackBufferSize =
-      media::AudioLatency::GetHighLatencyBufferSize(kHardwareSampleRate, 0);
+  int playbackBufferSize = media::AudioLatency::GetHighLatencyBufferSize(
+      kHardwareSampleRate, kHardwareBufferSize);
   SetupDevice(playbackLatencyHint);
 
   EXPECT_EQ(webaudio_device_->SampleRate(), kHardwareSampleRate);

content/shell/renderer/layout_test/layout_test_content_renderer_client.cc

@@ -213,8 +213,8 @@ LayoutTestContentRendererClient::OverrideCreateAudioDevice(
           media::AudioLatency::GetRtcBufferSize(hw_sample_rate, hw_buffer_size);
       break;
     case blink::WebAudioLatencyHint::kCategoryPlayback:
-      buffer_size =
-          media::AudioLatency::GetHighLatencyBufferSize(hw_sample_rate, 0);
+      buffer_size = media::AudioLatency::GetHighLatencyBufferSize(
+          hw_sample_rate, hw_buffer_size);
       break;
     case blink::WebAudioLatencyHint::kCategoryExact:
       buffer_size = media::AudioLatency::GetExactBufferSize(