Refactoring the way begin frame sources inside scheduler work.

cc/scheduler/begin_frame_source_unittest.cc

+// Copyright 2011 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 <deque>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/gtest_prod_util.h"
+#include "base/test/test_simple_task_runner.h"
+#include "cc/scheduler/begin_frame_source.h"
+#include "cc/test/begin_frame_args_test.h"
+#include "cc/test/scheduler_test_common.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// Macros to help set up expected calls on the MockBeginFrameObserver.
+#define EXPECT_BEGIN_FRAME_DROP(obs, frame_time, deadline, interval) \
+  {                                                                  \
+    ::testing::Expectation exp =                                     \
+        EXPECT_CALL((obs),                                           \
+                    OnBeginFrame(CreateBeginFrameArgsForTesting(     \
+                        frame_time, deadline, interval)))            \
+            .InSequence((obs).sequence);                             \
+  }
+
+#define EXPECT_BEGIN_FRAME_USED(obs, frame_time, deadline, interval)       \
+  {                                                                        \
+    BeginFrameArgs args =                                                  \
+        CreateBeginFrameArgsForTesting(frame_time, deadline, interval);    \
+    ::testing::Expectation exp =                                           \
+        EXPECT_CALL((obs), OnBeginFrame(args)).InSequence((obs).sequence); \
+    EXPECT_CALL((obs), LastUsedBeginFrameArgs())                           \
+        .Times(::testing::AnyNumber())                                     \
+        .After(exp)                                                        \
+        .WillRepeatedly(::testing::Return(args));                          \
+  }
+
+// Macros to send BeginFrameArgs on a FakeBeginFrameSink (and verify resulting
+// observer behaviour).
+#define SEND_BEGIN_FRAME(                                               \
+    args_equal_to, source, frame_time, deadline, interval)              \
+  {                                                                     \
+    BeginFrameArgs old_args = (source).TestLastUsedBeginFrameArgs();    \
+    BeginFrameArgs new_args =                                           \
+        CreateBeginFrameArgsForTesting(frame_time, deadline, interval); \
+    ASSERT_TRUE(!(old_args == new_args));                               \
+    (source).TestOnBeginFrame(new_args);                                \
+    EXPECT_EQ(args_equal_to, (source).TestLastUsedBeginFrameArgs());    \
+  }
+
+// When dropping LastUsedBeginFrameArgs **shouldn't** change.
+#define SEND_BEGIN_FRAME_DROP(source, frame_time, deadline, interval) \
+  SEND_BEGIN_FRAME(old_args, source, frame_time, deadline, interval);
+
+// When used LastUsedBeginFrameArgs **should** be updated.
+#define SEND_BEGIN_FRAME_USED(source, frame_time, deadline, interval) \
+  SEND_BEGIN_FRAME(new_args, source, frame_time, deadline, interval);
+
+namespace cc {
+namespace {
+
+class MockBeginFrameObserver : public BeginFrameObserver {
+ public:
+  MOCK_METHOD1(OnBeginFrame, void(const BeginFrameArgs&));
+  MOCK_CONST_METHOD0(LastUsedBeginFrameArgs, const BeginFrameArgs());
+
+  virtual void AsValueInto(base::debug::TracedValue* dict) const {
+    dict->SetString("type", "MockBeginFrameObserver");
+    dict->BeginDictionary("last_begin_frame_args");
+    LastUsedBeginFrameArgs().AsValueInto(dict);
+    dict->EndDictionary();
+  }
+
+  // A value different from the normal default returned by a BeginFrameObserver
+  // so it is easiable traced back here.
+  static const BeginFrameArgs kDefaultBeginFrameArgs;
+
+  MockBeginFrameObserver() {
+    // Set a "default" value returned by LastUsedBeginFrameArgs so that gMock
+    // doesn't fail an assert and instead returns useful information.
+    EXPECT_CALL(*this, LastUsedBeginFrameArgs())
+        .Times(::testing::AnyNumber())
+        .InSequence(sequence)
+        .WillRepeatedly(::testing::Return(kDefaultBeginFrameArgs));
+  }
+  virtual ~MockBeginFrameObserver() {}
+
+  ::testing::Sequence sequence;
+};
+
+TEST(MockBeginFrameObserverTest, ExpectOnBeginFrame) {
+  ::testing::NiceMock<MockBeginFrameObserver> obs;
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            MockBeginFrameObserver::kDefaultBeginFrameArgs);
+
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(
+      100, 200, 300));  // One call to LastUsedBeginFrameArgs
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(100, 200, 300));
+
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(
+      400, 600, 300));  // Multiple calls to LastUsedBeginFrameArgs
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(400, 600, 300));
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(400, 600, 300));
+
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(
+      700, 900, 300));  // No calls to LastUsedBeginFrameArgs
+}
+
+TEST(MockBeginFrameObserverTest, ExpectOnBeginFrameStatus) {
+  ::testing::NiceMock<MockBeginFrameObserver> obs;
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_DROP(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_DROP(obs, 450, 650, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            MockBeginFrameObserver::kDefaultBeginFrameArgs);
+
+  // Used
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(100, 200, 300));
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(100, 200, 300));
+
+  // Dropped
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(400, 600, 300));
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(100, 200, 300));
+
+  // Dropped
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(450, 650, 300));
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(100, 200, 300));
+
+  // Used
+  obs.OnBeginFrame(CreateBeginFrameArgsForTesting(700, 900, 300));
+  EXPECT_EQ(obs.LastUsedBeginFrameArgs(),
+            CreateBeginFrameArgsForTesting(700, 900, 300));
+}
+
+const BeginFrameArgs MockBeginFrameObserver::kDefaultBeginFrameArgs =
+    CreateBeginFrameArgsForTesting(-1, -1, -1);
+
+// BeginFrameObserverMixIn testing ---------------------------------------
+class MockMinimalBeginFrameObserverMixIn : public BeginFrameObserverMixIn {
+ public:
+  MOCK_METHOD1(OnBeginFrameMixInDelegate, bool(const BeginFrameArgs&));
+  int64_t dropped_begin_frame_args() const { return dropped_begin_frame_args_; }
+};
+
+TEST(BeginFrameObserverMixInTest, OnBeginFrameImplementation) {
+  using ::testing::Return;
+  MockMinimalBeginFrameObserverMixIn obs;
+  ::testing::InSequence ordered;  // These calls should be ordered
+
+  // Initial conditions
+  EXPECT_EQ(BeginFrameArgs(), obs.LastUsedBeginFrameArgs());
+  EXPECT_EQ(0, obs.dropped_begin_frame_args());
+
+#ifndef NDEBUG
+  EXPECT_DEATH({ obs.OnBeginFrame(BeginFrameArgs()); }, "");
+#endif
+
+  BeginFrameArgs args1 = CreateBeginFrameArgsForTesting(100, 200, 300);
+  EXPECT_CALL(obs, OnBeginFrameMixInDelegate(args1)).WillOnce(Return(true));
+  obs.OnBeginFrame(args1);
+  EXPECT_EQ(args1, obs.LastUsedBeginFrameArgs());
+  EXPECT_EQ(0, obs.dropped_begin_frame_args());
+
+#ifndef NDEBUG
+  EXPECT_DEATH(
+      { obs.OnBeginFrame(CreateBeginFrameArgsForTesting(50, 200, 300)); }, "");
+#endif
+
+  // Returning false shouldn't update the LastUsedBeginFrameArgs value.
+  BeginFrameArgs args2 = CreateBeginFrameArgsForTesting(200, 300, 400);
+  EXPECT_CALL(obs, OnBeginFrameMixInDelegate(args2)).WillOnce(Return(false));
+  obs.OnBeginFrame(args2);
+  EXPECT_EQ(args1, obs.LastUsedBeginFrameArgs());
+  EXPECT_EQ(1, obs.dropped_begin_frame_args());
+
+  BeginFrameArgs args3 = CreateBeginFrameArgsForTesting(150, 300, 400);
+  EXPECT_CALL(obs, OnBeginFrameMixInDelegate(args3)).WillOnce(Return(true));
+  obs.OnBeginFrame(args3);
+  EXPECT_EQ(args3, obs.LastUsedBeginFrameArgs());
+  EXPECT_EQ(1, obs.dropped_begin_frame_args());
+}
+
+// BeginFrameSource testing ----------------------------------------------
+TEST(BeginFrameSourceMixInTest, ObserverManipulation) {
+  MockBeginFrameObserver obs;
+  MockBeginFrameObserver otherObs;
+  FakeBeginFrameSource source;
+
+  source.AddObserver(&obs);
+  EXPECT_EQ(&obs, source.GetObserver());
+
+#ifndef NDEBUG
+  // Adding an observer when an observer already exists should DCHECK fail.
+  EXPECT_DEATH({ source.AddObserver(&otherObs); }, "");
+
+  // Removing wrong observer should DCHECK fail.
+  EXPECT_DEATH({ source.RemoveObserver(&otherObs); }, "");
+
+  // Removing an observer when there is no observer should DCHECK fail.
+  EXPECT_DEATH({
+                 source.RemoveObserver(&obs);
+                 source.RemoveObserver(&obs);
+               },
+               "");
+#endif
+  source.RemoveObserver(&obs);
+
+  source.AddObserver(&otherObs);
+  EXPECT_EQ(&otherObs, source.GetObserver());
+  source.RemoveObserver(&otherObs);
+}
+
+TEST(BeginFrameSourceMixInTest, Observer) {
+  FakeBeginFrameSource source;
+  MockBeginFrameObserver obs;
+  source.AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_DROP(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_DROP(obs, 450, 650, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+
+  SEND_BEGIN_FRAME_USED(source, 100, 200, 300);
+  SEND_BEGIN_FRAME_DROP(source, 400, 600, 300);
+  SEND_BEGIN_FRAME_DROP(source, 450, 650, 300);
+  SEND_BEGIN_FRAME_USED(source, 700, 900, 300);
+}
+
+TEST(BeginFrameSourceMixInTest, NoObserver) {
+  FakeBeginFrameSource source;
+  SEND_BEGIN_FRAME_DROP(source, 100, 200, 300);
+}
+
+TEST(BeginFrameSourceMixInTest, NeedsBeginFrames) {
+  FakeBeginFrameSource source;
+  EXPECT_FALSE(source.NeedsBeginFrames());
+  source.SetNeedsBeginFrames(true);
+  EXPECT_TRUE(source.NeedsBeginFrames());
+  source.SetNeedsBeginFrames(false);
+  EXPECT_FALSE(source.NeedsBeginFrames());
+}
+
+class LoopingBeginFrameObserver : public BeginFrameObserverMixIn {
+ public:
+  BeginFrameSource* source_;
+
+  virtual void AsValueInto(base::debug::TracedValue* dict) const OVERRIDE {
+    dict->SetString("type", "LoopingBeginFrameObserver");
+    dict->BeginDictionary("source");
+    source_->AsValueInto(dict);
+    dict->EndDictionary();
+  }
+
+ protected:
+  // BeginFrameObserverMixIn
+  virtual bool OnBeginFrameMixInDelegate(const BeginFrameArgs& args) OVERRIDE {
+    return true;
+  }
+};
+
+TEST(BeginFrameSourceMixInTest, DetectAsValueIntoLoop) {
+  LoopingBeginFrameObserver obs;
+  FakeBeginFrameSource source;
+
+  obs.source_ = &source;
+  source.AddObserver(&obs);
+
+  scoped_refptr<base::debug::TracedValue> state =
+      new base::debug::TracedValue();
+  source.AsValueInto(state.get());
+}
+
+// BackToBackBeginFrameSource testing -----------------------------------------
+class TestBackToBackBeginFrameSource : public BackToBackBeginFrameSource {
+ public:
+  static scoped_ptr<TestBackToBackBeginFrameSource> Create(
+      scoped_refptr<TestNowSource> now_src,
+      base::SingleThreadTaskRunner* task_runner) {
+    return make_scoped_ptr(
+        new TestBackToBackBeginFrameSource(now_src, task_runner));
+  }
+
+ protected:
+  TestBackToBackBeginFrameSource(scoped_refptr<TestNowSource> now_src,
+                                 base::SingleThreadTaskRunner* task_runner)
+      : BackToBackBeginFrameSource(task_runner), now_src_(now_src) {}
+
+  virtual base::TimeTicks Now() OVERRIDE { return now_src_->Now(); }
+
+  scoped_refptr<TestNowSource> now_src_;
+};
+
+class BackToBackBeginFrameSourceTest : public ::testing::Test {
+ public:
+  static const int64_t kDeadline;
+  static const int64_t kInterval;
+
+  scoped_refptr<TestNowSource> now_src_;
+  scoped_refptr<OrderedSimpleTaskRunner> task_runner_;
+  scoped_ptr<TestBackToBackBeginFrameSource> source_;
+  scoped_ptr<MockBeginFrameObserver> obs_;
+
+  virtual void SetUp() OVERRIDE {
+    now_src_ = TestNowSource::Create(1000);
+    task_runner_ =
+        make_scoped_refptr(new OrderedSimpleTaskRunner(now_src_, false));
+    task_runner_->SetRunTaskLimit(1);
+    source_ =
+        TestBackToBackBeginFrameSource::Create(now_src_, task_runner_.get());
+    obs_ = make_scoped_ptr(new ::testing::StrictMock<MockBeginFrameObserver>());
+    source_->AddObserver(obs_.get());
+  }
+
+  virtual void TearDown() OVERRIDE { obs_.reset(); }
+};
+
+const int64_t BackToBackBeginFrameSourceTest::kDeadline =
+    BeginFrameArgs::DefaultInterval().ToInternalValue();
+
+const int64_t BackToBackBeginFrameSourceTest::kInterval =
+    BeginFrameArgs::DefaultInterval().ToInternalValue();
+
+TEST_F(BackToBackBeginFrameSourceTest, SetNeedsBeginFramesSendsBeginFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  EXPECT_TRUE(task_runner_->HasPendingTasks());
+  task_runner_->RunUntilIdle();
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1100, 1100 + kDeadline, kInterval);
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest,
+       DidFinishFrameThenSetNeedsBeginFramesProducesNoFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  source_->SetNeedsBeginFrames(false);
+  source_->DidFinishFrame(0);
+
+  EXPECT_FALSE(task_runner_->HasPendingTasks());
+}
+
+TEST_F(BackToBackBeginFrameSourceTest,
+       SetNeedsBeginFramesThenDidFinishFrameProducesNoFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  source_->SetNeedsBeginFrames(false);
+
+  EXPECT_TRUE(task_runner_->HasPendingTasks());
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest,
+       DidFinishFrameThenTogglingSetNeedsBeginFramesProducesCorrectFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+
+  source_->SetNeedsBeginFrames(false);
+  now_src_->AdvanceNowMicroseconds(10);
+  source_->DidFinishFrame(0);
+  now_src_->AdvanceNowMicroseconds(10);
+  source_->SetNeedsBeginFrames(false);
+  now_src_->AdvanceNowMicroseconds(10);
+  source_->SetNeedsBeginFrames(true);
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1130, 1130 + kDeadline, kInterval);
+  EXPECT_TRUE(task_runner_->HasPendingTasks());
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest,
+       TogglingSetNeedsBeginFramesThenDidFinishFrameProducesCorrectFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  now_src_->AdvanceNowMicroseconds(10);
+  source_->SetNeedsBeginFrames(false);
+  now_src_->AdvanceNowMicroseconds(10);
+  source_->SetNeedsBeginFrames(true);
+  now_src_->AdvanceNowMicroseconds(10);
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1130, 1130 + kDeadline, kInterval);
+  EXPECT_TRUE(task_runner_->HasPendingTasks());
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest, DidFinishFrameNeedsBeginFrameFalse) {
+  source_->SetNeedsBeginFrames(false);
+  source_->DidFinishFrame(0);
+  EXPECT_FALSE(task_runner_->RunPendingTasks());
+}
+
+TEST_F(BackToBackBeginFrameSourceTest, DidFinishFrameRemainingFrames) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+
+  source_->DidFinishFrame(3);
+  EXPECT_FALSE(task_runner_->HasPendingTasks());
+  source_->DidFinishFrame(2);
+  EXPECT_FALSE(task_runner_->HasPendingTasks());
+  source_->DidFinishFrame(1);
+  EXPECT_FALSE(task_runner_->HasPendingTasks());
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1100, 1100 + kDeadline, kInterval);
+  source_->DidFinishFrame(0);
+  EXPECT_EQ(base::TimeDelta(), task_runner_->DelayToNextTaskTime());
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest, DidFinishFrameMultipleCallsIdempotent) {
+  source_->SetNeedsBeginFrames(true);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  source_->DidFinishFrame(0);
+  source_->DidFinishFrame(0);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1100, 1100 + kDeadline, kInterval);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  source_->DidFinishFrame(0);
+  source_->DidFinishFrame(0);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1200, 1200 + kDeadline, kInterval);
+  task_runner_->RunUntilIdle();
+}
+
+TEST_F(BackToBackBeginFrameSourceTest, DelayInPostedTaskProducesCorrectFrame) {
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1000, 1000 + kDeadline, kInterval);
+  source_->SetNeedsBeginFrames(true);
+  task_runner_->RunUntilIdle();
+
+  now_src_->AdvanceNowMicroseconds(100);
+  source_->DidFinishFrame(0);
+  now_src_->AdvanceNowMicroseconds(50);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 1150, 1150 + kDeadline, kInterval);
+
+  EXPECT_TRUE(task_runner_->HasPendingTasks());
+  task_runner_->RunUntilIdle();
+}
+
+// SyntheticBeginFrameSource testing ------------------------------------------
+class SyntheticBeginFrameSourceTest : public ::testing::Test {
+ public:
+  scoped_refptr<TestNowSource> now_src_;
+  scoped_refptr<OrderedSimpleTaskRunner> task_runner_;
+  scoped_ptr<TestSyntheticBeginFrameSource> source_;
+  scoped_ptr<MockBeginFrameObserver> obs_;
+
+  virtual void SetUp() OVERRIDE {
+    now_src_ = TestNowSource::Create(1000);
+    task_runner_ =
+        make_scoped_refptr(new OrderedSimpleTaskRunner(now_src_, false));
+    source_ = TestSyntheticBeginFrameSource::Create(
+        now_src_, task_runner_.get(), base::TimeDelta::FromMicroseconds(10000));
+    obs_ = make_scoped_ptr(new MockBeginFrameObserver());
+    source_->AddObserver(obs_.get());
+  }
+
+  virtual void TearDown() OVERRIDE { obs_.reset(); }
+};
+
+TEST_F(SyntheticBeginFrameSourceTest,
+       SetNeedsBeginFramesCallsOnBeginFrameWithMissedTick) {
+  now_src_->SetNowMicroseconds(10010);
+  EXPECT_CALL((*obs_),
+              OnBeginFrame(CreateTypedBeginFrameArgsForTesting(
+                  10000, 20000, 10000, BeginFrameArgs::MISSED)));
+  source_->SetNeedsBeginFrames(true);  // Should cause the last tick to be sent
+  // No tasks should need to be run for this to occur.
+}
+
+TEST_F(SyntheticBeginFrameSourceTest,
+       SetNeedsBeginFramesCallsCausesOnBeginFrame) {
+  source_->SetNeedsBeginFrames(true);
+  EXPECT_EQ(10000, task_runner_->NextTaskTime().ToInternalValue());
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 10000, 20000, 10000);
+  now_src_->SetNowMicroseconds(10010);
+  task_runner_->RunPendingTasks();
+}
+
+TEST_F(SyntheticBeginFrameSourceTest, BasicOperation) {
+  task_runner_->SetAutoAdvanceNowToPendingTasks(true);
+
+  source_->SetNeedsBeginFrames(true);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 10000, 20000, 10000);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 20000, 30000, 10000);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 30000, 40000, 10000);
+  task_runner_->RunUntilTime(base::TimeTicks::FromInternalValue(30001));
+
+  source_->SetNeedsBeginFrames(false);
+  // No new frames....
+  task_runner_->RunUntilTime(base::TimeTicks::FromInternalValue(60000));
+}
+
+TEST_F(SyntheticBeginFrameSourceTest, VSyncChanges) {
+  task_runner_->SetAutoAdvanceNowToPendingTasks(true);
+  source_->SetNeedsBeginFrames(true);
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 10000, 20000, 10000);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 20000, 30000, 10000);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 30000, 40000, 10000);
+  task_runner_->RunUntilTime(base::TimeTicks::FromInternalValue(30001));
+
+  // Update the vsync information
+  source_->OnUpdateVSyncParameters(base::TimeTicks::FromInternalValue(27500),
+                                   base::TimeDelta::FromMicroseconds(10001));
+
+  EXPECT_BEGIN_FRAME_USED(*obs_, 40000, 47502, 10001);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 47502, 57503, 10001);
+  EXPECT_BEGIN_FRAME_USED(*obs_, 57503, 67504, 10001);
+  task_runner_->RunUntilTime(base::TimeTicks::FromInternalValue(60000));
+}
+
+// BeginFrameSourceMultiplexer testing -----------------------------------
+class BeginFrameSourceMultiplexerTest : public ::testing::Test {
+ protected:
+  virtual void SetUp() OVERRIDE {
+    mux_ = BeginFrameSourceMultiplexer::Create();
+
+    source1_store_ = make_scoped_ptr(new FakeBeginFrameSource());
+    source2_store_ = make_scoped_ptr(new FakeBeginFrameSource());
+    source3_store_ = make_scoped_ptr(new FakeBeginFrameSource());
+
+    source1_ = source1_store_.get();
+    source2_ = source2_store_.get();
+    source3_ = source3_store_.get();
+  }
+
+  virtual void TearDown() OVERRIDE {
+    // Make sure the mux is torn down before the sources.
+    mux_.reset();
+  }
+
+  scoped_ptr<BeginFrameSourceMultiplexer> mux_;
+  FakeBeginFrameSource* source1_;
+  FakeBeginFrameSource* source2_;
+  FakeBeginFrameSource* source3_;
+
+ private:
+  scoped_ptr<FakeBeginFrameSource> source1_store_;
+  scoped_ptr<FakeBeginFrameSource> source2_store_;
+  scoped_ptr<FakeBeginFrameSource> source3_store_;
+};
+
+TEST_F(BeginFrameSourceMultiplexerTest, SourcesManipulation) {
+  EXPECT_EQ(NULL, mux_->ActiveSource());
+
+  mux_->AddSource(source1_);
+  EXPECT_EQ(source1_, mux_->ActiveSource());
+
+  mux_->SetActiveSource(NULL);
+  EXPECT_EQ(NULL, mux_->ActiveSource());
+
+  mux_->SetActiveSource(source1_);
+
+#ifndef NDEBUG
+  // Setting a source which isn't in the mux as active should DCHECK fail.
+  EXPECT_DEATH({ mux_->SetActiveSource(source2_); }, "");
+
+  // Adding a source which is already added should DCHECK fail.
+  EXPECT_DEATH({ mux_->AddSource(source1_); }, "");
+
+  // Removing a source which isn't in the mux should DCHECK fail.
+  EXPECT_DEATH({ mux_->RemoveSource(source2_); }, "");
+
+  // Removing the active source fails
+  EXPECT_DEATH({ mux_->RemoveSource(source1_); }, "");
+#endif
+
+  // Test manipulation doesn't segfault.
+  mux_->AddSource(source2_);
+  mux_->RemoveSource(source2_);
+
+  mux_->AddSource(source2_);
+  mux_->SetActiveSource(source2_);
+  EXPECT_EQ(source2_, mux_->ActiveSource());
+
+  mux_->RemoveSource(source1_);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, NeedsBeginFrames) {
+  mux_->AddSource(source1_);
+  mux_->AddSource(source2_);
+  mux_->SetActiveSource(source1_);
+  EXPECT_EQ(source1_->NeedsBeginFrames(), false);
+  EXPECT_EQ(source2_->NeedsBeginFrames(), false);
+
+  // Check SetNeedsFrames works
+  mux_->SetNeedsBeginFrames(true);
+  EXPECT_EQ(source1_->NeedsBeginFrames(), true);
+  EXPECT_EQ(source2_->NeedsBeginFrames(), false);
+
+  mux_->SetNeedsBeginFrames(false);
+  EXPECT_EQ(source1_->NeedsBeginFrames(), false);
+  EXPECT_EQ(source2_->NeedsBeginFrames(), false);
+
+  // Checking that switching the source makes SetNeedsFrames on the
+  // subsources correctly.
+  mux_->SetNeedsBeginFrames(true);
+
+  mux_->SetActiveSource(source1_);
+  EXPECT_EQ(source1_->NeedsBeginFrames(), true);
+  EXPECT_EQ(source2_->NeedsBeginFrames(), false);
+
+  mux_->SetActiveSource(source2_);
+  EXPECT_EQ(source1_->NeedsBeginFrames(), false);
+  EXPECT_EQ(source2_->NeedsBeginFrames(), true);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, BeginFramesSimple) {
+  mux_->AddSource(source1_);
+  mux_->AddSource(source2_);
+  mux_->SetActiveSource(source1_);
+
+  MockBeginFrameObserver obs;
+  mux_->AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 400, 600, 300);
+
+  mux_->SetActiveSource(source1_);
+
+  SEND_BEGIN_FRAME_USED(*source1_, 100, 200, 300);
+  SEND_BEGIN_FRAME_DROP(*source2_, 200, 500, 300);
+
+  mux_->SetActiveSource(source2_);
+  SEND_BEGIN_FRAME_USED(*source2_, 400, 600, 300);
+  SEND_BEGIN_FRAME_DROP(*source1_, 500, 700, 300);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, BeginFramesBackwardsProtection) {
+  mux_->AddSource(source1_);
+  mux_->AddSource(source2_);
+
+  MockBeginFrameObserver obs;
+  mux_->AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 1000, 1200, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 1001, 1201, 301);
+
+  mux_->SetActiveSource(source1_);
+  SEND_BEGIN_FRAME_USED(*source1_, 400, 600, 300);
+  SEND_BEGIN_FRAME_USED(*source1_, 700, 900, 300);
+
+  mux_->SetActiveSource(source2_);
+  SEND_BEGIN_FRAME_DROP(*source2_, 699, 899, 300);
+  SEND_BEGIN_FRAME_USED(*source2_, 1000, 1200, 300);
+
+  mux_->SetActiveSource(source1_);
+  SEND_BEGIN_FRAME_USED(*source1_, 1001, 1201, 301);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, MinimumIntervalNegativeFails) {
+#ifndef NDEBUG
+  EXPECT_DEATH(
+      { mux_->SetMinimumInterval(base::TimeDelta::FromInternalValue(-100)); },
+      "");
+#endif
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, MinimumIntervalZero) {
+  mux_->SetMinimumInterval(base::TimeDelta());
+  mux_->AddSource(source1_);
+
+  MockBeginFrameObserver obs;
+  mux_->AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+
+  SEND_BEGIN_FRAME_USED(*source1_, 100, 200, 300);
+  SEND_BEGIN_FRAME_USED(*source1_, 400, 600, 300);
+  SEND_BEGIN_FRAME_USED(*source1_, 700, 900, 300);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, MinimumIntervalBasic) {
+  mux_->SetMinimumInterval(base::TimeDelta::FromInternalValue(600));
+  mux_->AddSource(source1_);
+
+  MockBeginFrameObserver obs;
+  mux_->AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 100, 200, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+
+  SEND_BEGIN_FRAME_USED(*source1_, 100, 200, 300);
+  SEND_BEGIN_FRAME_DROP(*source1_, 400, 600, 300);
+  SEND_BEGIN_FRAME_USED(*source1_, 700, 900, 300);
+}
+
+TEST_F(BeginFrameSourceMultiplexerTest, MinimumIntervalWithMultipleSources) {
+  mux_->SetMinimumInterval(base::TimeDelta::FromMicroseconds(150));
+  mux_->AddSource(source1_);
+  mux_->AddSource(source2_);
+
+  MockBeginFrameObserver obs;
+  mux_->AddObserver(&obs);
+  EXPECT_BEGIN_FRAME_USED(obs, 400, 600, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 700, 900, 300);
+  EXPECT_BEGIN_FRAME_USED(obs, 1050, 1250, 300);
+
+  mux_->SetActiveSource(source1_);
+  SEND_BEGIN_FRAME_USED(*source1_, 400, 600, 300);
+  SEND_BEGIN_FRAME_USED(*source1_, 700, 900, 300);
+
+  mux_->SetActiveSource(source2_);
+  SEND_BEGIN_FRAME_DROP(*source2_, 750, 1050, 300);
+  SEND_BEGIN_FRAME_USED(*source2_, 1050, 1250, 300);
+
+  mux_->SetActiveSource(source1_);
+  SEND_BEGIN_FRAME_DROP(*source2_, 1100, 1400, 300);
+}
+
+}  // namespace
+}  // namespace cc