Raise time limits for AudioSyncReader::Read() for test on Fuchsia.

Fuchsia, running on the test bots, was sometimes taking too long to
return data to AudioSyncReader (observed 21ms, max 20ms), which
lead to test flakes.


Bug: 838367
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: If2e25357acd70eaa28c6e618e696cc39ea9ba372
Reviewed-on: https://chromium-review.googlesource.com/1036196
Commit-Queue: Kevin Marshall <kmarshall@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555128}

media/audio/audio_output_device_unittest.cc

@@ -19,6 +19,7 @@
 #include "base/task_runner.h"
 #include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "build/build_config.h"
 #include "media/audio/audio_sync_reader.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -342,6 +343,15 @@ struct TestEnvironment {
         /*log callback*/ base::DoNothing(), params, std::move(shared_memory),
         std::move(browser_socket));
     time_stamp = base::TimeTicks::Now();
+
+#if defined(OS_FUCHSIA)
+    // Raise the timeout limits to reduce bot flakiness.
+    // Fuchsia's task scheduler suffers from bad jitter on systems running many
+    // tests simultaneously on nested virtualized deployments (e.g. test bots),
+    // leading some read operations to randomly timeout.
+    reader->set_max_wait_timeout_for_test(
+        base::TimeDelta::FromMilliseconds(50));
+#endif
   }
 
   base::CancelableSyncSocket renderer_socket;

media/audio/audio_sync_reader.h

@@ -57,6 +57,10 @@ class MEDIA_EXPORT AudioSyncReader : public AudioOutputController::SyncReader {
     return shared_memory_.get();
   }
 
+  void set_max_wait_timeout_for_test(base::TimeDelta time) {
+    maximum_wait_time_ = time;
+  }
+
   // AudioOutputController::SyncReader implementations.
   void RequestMoreData(base::TimeDelta delay,
                        base::TimeTicks delay_timestamp,
@@ -97,7 +101,7 @@ class MEDIA_EXPORT AudioSyncReader : public AudioOutputController::SyncReader {
 
   // The maximum amount of time to wait for data from the renderer.  Calculated
   // from the parameters given at construction.
-  const base::TimeDelta maximum_wait_time_;
+  base::TimeDelta maximum_wait_time_;
 
   // The index of the audio buffer we're expecting to be sent from the renderer;
   // used to block with timeout for audio data.