Replace MessageLoop with ScopedTaskEnvironment in RTCRtpSenderTest.

This test base instantiates a content::ChildProcess to provide the
expected environment for the code-under-test. ChildProcess expects to
either run in the context of ScopedTaskEnvironment, in tests, or to
need to initialize the TaskScheduler itself.

Add a ScopedTaskEnvironment to the test base, otherwise the ChildProcess
TaskScheduler will "leak" and break later tests.

Re-enables the RTCVideoDecoderAdapterTest tests, that had been
broken by this issue.

TBR=hbos

Bug: 875278, 875301, 875336
Change-Id: I8a7ee1f42e62241d48720c41897bdcadbcd26bdf
Reviewed-on: https://chromium-review.googlesource.com/1180408
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584298}

content/renderer/media/webrtc/rtc_rtp_receiver_unittest.cc

@@ -8,10 +8,10 @@
 
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/waitable_event.h"
+#include "base/test/scoped_task_environment.h"
 #include "content/child/child_process.h"
 #include "content/renderer/media/webrtc/mock_peer_connection_dependency_factory.h"
 #include "content/renderer/media/webrtc/mock_peer_connection_impl.h"
@@ -97,9 +97,10 @@ class RTCRtpReceiverTest : public ::testing::Test {
     run_loop->Quit();
   }
 
-  // Message loop and child processes is needed for task queues and threading to
-  // work, as is necessary to create tracks and adapters.
-  base::MessageLoop message_loop_;
+  // Code under test expects to be run in a process with an initialized
+  // ChildProcess, which requires TaskScheduler, and a main-thread MessageLoop,
+  // which the ScopedTaskEnvironment also provides.
+  base::test::ScopedTaskEnvironment task_environment_;
   ChildProcess child_process_;
 
   std::unique_ptr<MockPeerConnectionDependencyFactory> dependency_factory_;

content/renderer/media/webrtc/rtc_rtp_sender_unittest.cc

@@ -7,9 +7,9 @@
 #include <memory>
 
 #include "base/memory/ref_counted.h"
-#include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
+#include "base/test/scoped_task_environment.h"
 #include "build/build_config.h"
 #include "content/child/child_process.h"
 #include "content/renderer/media/stream/media_stream_audio_source.h"
@@ -136,9 +136,10 @@ class RTCRtpSenderTest : public ::testing::Test {
     return *result_holder;
   }
 
-  // Message loop and child processes is needed for task queues and threading to
-  // work, as is necessary to create tracks and adapters.
-  base::MessageLoop message_loop_;
+  // Code under test expects to be run in a process with an initialized
+  // ChildProcess, which requires TaskScheduler, and a main-thread MessageLoop,
+  // which the ScopedTaskEnvironment also provides.
+  base::test::ScopedTaskEnvironment task_environment_;
   ChildProcess child_process_;
 
   std::unique_ptr<MockPeerConnectionDependencyFactory> dependency_factory_;

content/renderer/media/webrtc/rtc_video_decoder_adapter_unittest.cc

@@ -203,19 +203,16 @@ class RTCVideoDecoderAdapterTest : public ::testing::Test {
   DISALLOW_COPY_AND_ASSIGN(RTCVideoDecoderAdapterTest);
 };
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Lifecycle) {
+TEST_F(RTCVideoDecoderAdapterTest, Lifecycle) {
   ASSERT_TRUE(BasicSetup());
   ASSERT_TRUE(BasicTeardown());
 }
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_InitializationFailure) {
+TEST_F(RTCVideoDecoderAdapterTest, InitializationFailure) {
   ASSERT_FALSE(CreateAndInitialize(false));
 }
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode) {
+TEST_F(RTCVideoDecoderAdapterTest, Decode) {
   ASSERT_TRUE(BasicSetup());
 
   EXPECT_CALL(*video_decoder_, Decode(_, _))
@@ -228,8 +225,7 @@ TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode) {
   media_thread_.FlushForTesting();
 }
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode_Error) {
+TEST_F(RTCVideoDecoderAdapterTest, Decode_Error) {
   ASSERT_TRUE(BasicSetup());
 
   EXPECT_CALL(*video_decoder_, Decode(_, _))
@@ -241,8 +237,7 @@ TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode_Error) {
   ASSERT_EQ(Decode(1), WEBRTC_VIDEO_CODEC_FALLBACK_SOFTWARE);
 }
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode_Hang_Short) {
+TEST_F(RTCVideoDecoderAdapterTest, Decode_Hang_Short) {
   ASSERT_TRUE(BasicSetup());
 
   // Ignore Decode() calls.
@@ -260,8 +255,7 @@ TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode_Hang_Short) {
   FAIL();
 }
 
-// Flakily crashing on various platforms. See https://crbug.com/875278.
-TEST_F(RTCVideoDecoderAdapterTest, DISABLED_Decode_Hang_Long) {
+TEST_F(RTCVideoDecoderAdapterTest, Decode_Hang_Long) {
   ASSERT_TRUE(BasicSetup());
 
   // Ignore Decode() calls.