Implement idle task scheduling.

Source/platform/scheduler/SchedulerTest.cpp

Index: Source/platform/scheduler/SchedulerTest.cpp
diff --git a/Source/platform/scheduler/SchedulerTest.cpp b/Source/platform/scheduler/SchedulerTest.cpp
index 75789407a196a6030bd9164a5e2ecf4d62205cf9..7822ccefde52d74cc75379e4cec3a55403bdb1a3 100644
--- a/Source/platform/scheduler/SchedulerTest.cpp
+++ b/Source/platform/scheduler/SchedulerTest.cpp
@@ -239,9 +239,11 @@ void unorderedTestTask(int value, int* result)
     *result += value;
 }
 
-void idleTestTask(int value, int* result, double allottedTime)
+void idleTestTask(bool* taskRun, double expectedDeadline, double deadlineSeconds)
 {
-    *result += value;
+    EXPECT_EQ(false, *taskRun);
+    EXPECT_EQ(expectedDeadline, deadlineSeconds);
+    *taskRun = true;
 }
 
 TEST_F(SchedulerTest, TestPostTask)
@@ -293,14 +295,30 @@ TEST_F(SchedulerTest, TestSharedTimer)
 
 TEST_F(SchedulerTest, TestIdleTask)
 {
-    // TODO: Check task allottedTime when implemented in the scheduler.
-    int result = 0;
-    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
-    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, 1, &result));
+    bool taskRun = false;
+    double firstDeadline = 1.1;
+    double secondDeadline = 2.3;
+    m_platformSupport.setMonotonicTimeForTest(0.1);
+
+    m_scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(&idleTestTask, &taskRun, secondDeadline));
+
+    runPendingTasks();
+    EXPECT_FALSE(taskRun); // Shouldn't run yet as no willBeginFrame.
+
+    m_scheduler->willBeginFrame(firstDeadline);
+    runPendingTasks();
+    EXPECT_FALSE(taskRun); // Shouldn't run yet as no didCommitFrameToCompositor.
+
+    m_platformSupport.setMonotonicTimeForTest(firstDeadline + 0.1);
+    m_scheduler->didCommitFrameToCompositor();
+    runPendingTasks();
+    EXPECT_FALSE(taskRun); // We missed the deadline.
+
+    m_scheduler->willBeginFrame(secondDeadline);
+    m_platformSupport.setMonotonicTimeForTest(secondDeadline - 0.1);
+    m_scheduler->didCommitFrameToCompositor();
     runPendingTasks();
-    EXPECT_EQ(4, result);
+    EXPECT_TRUE(taskRun);
 }
 
 TEST_F(SchedulerTest, TestTaskPrioritization_normalPolicy)