Add a simple, safe gain PostProcessor.

chromecast/media/cma/backend/alsa/post_processors/saturated_gain_unittest.cc

+// Copyright 2017 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 <string>
+#include <vector>
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/stringprintf.h"
+#include "chromecast/media/cma/backend/alsa/post_processors/post_processor_unittest.h"
+#include "chromecast/media/cma/backend/alsa/post_processors/saturated_gain.h"
+
+namespace chromecast {
+namespace media {
+namespace post_processor_test {
+
+namespace {
+
+const char* kConfigTemplate =
+    R"config({"gain_db": %f})config";
+
+std::string MakeConfigString(float gain_db) {
+  return base::StringPrintf(kConfigTemplate, gain_db);
+}
+
+}  // namespace
+
+// Default tests from post_processor_test
+TEST_P(PostProcessorTest, TestDelay) {
+  std::string config = MakeConfigString(0.0);
+  auto pp =
+      base::WrapUnique(AudioPostProcessorShlib_Create(config, kNumChannels));
+  TestDelay(pp.get(), sample_rate_);
+}
+
+TEST_P(PostProcessorTest, TestRinging) {
+  std::string config = MakeConfigString(0.0);
+  auto pp =
+      base::WrapUnique(AudioPostProcessorShlib_Create(config, kNumChannels));
+  TestRingingTime(pp.get(), sample_rate_);
+}
+
+// Also tests clipping (by attempting to set gain way too high).
+TEST_P(PostProcessorTest, TestPassthrough) {
+  std::string config = MakeConfigString(100.0);
+  auto pp =
+      base::WrapUnique(AudioPostProcessorShlib_Create(config, kNumChannels));
+  TestPassthrough(pp.get(), sample_rate_);
+}
+
+}  // namespace post_processor_test
+}  // namespace media
+}  // namespace chromecast