Make OS audio buffer size limits visible.

content/shell/renderer/layout_test/layout_test_content_renderer_client.cc

Index: content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
diff --git a/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc b/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
index bf0ffcac6a2a83aca8359259c36f478e4b344387..f05701f945fbcc76907dfd67f2c8953917b7d283 100644
--- a/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
+++ b/content/shell/renderer/layout_test/layout_test_content_renderer_client.cc
@@ -30,6 +30,7 @@
 #include "content/shell/test_runner/web_view_test_proxy.h"
 #include "content/test/mock_webclipboard_impl.h"
 #include "gin/modules/module_registry.h"
+#include "media/audio/audio_manager.h"
 #include "media/base/audio_latency.h"
 #include "media/media_features.h"
 #include "third_party/WebKit/public/platform/WebAudioLatencyHint.h"
@@ -217,11 +218,11 @@ LayoutTestContentRendererClient::OverrideCreateAudioDevice(
           media::AudioLatency::GetHighLatencyBufferSize(hw_sample_rate, 0);
       break;
     case blink::WebAudioLatencyHint::kCategoryExact:
-      // TODO(andrew.macpherson@soundtrap.com): http://crbug.com/708917
       buffer_size = std::min(
-          4096, media::AudioLatency::GetExactBufferSize(
-                    base::TimeDelta::FromSecondsD(latency_hint.Seconds()),
-                    hw_sample_rate, hw_buffer_size));
+          media::AudioManager::GetMaximumAudioBufferSize(hw_sample_rate),
+          media::AudioLatency::GetExactBufferSize(
+              base::TimeDelta::FromSecondsD(latency_hint.Seconds()),
+              hw_sample_rate, hw_buffer_size));
       break;
     default:
       NOTREACHED();