Implement idle task scheduling.

Source/platform/scheduler/TracedTask.cpp

Index: Source/platform/scheduler/TracedTask.cpp
diff --git a/Source/platform/scheduler/TracedTask.cpp b/Source/platform/scheduler/TracedTask.cpp
index d4e1fa69f78c4535379dfbff2f49e00138acad4f..ba9518cb44ece5f2b6f7c4fb47b5d03acf2882cf 100644
--- a/Source/platform/scheduler/TracedTask.cpp
+++ b/Source/platform/scheduler/TracedTask.cpp
@@ -4,15 +4,45 @@
 
 #include "config.h"
 #include "platform/scheduler/TracedTask.h"
+#include "platform/scheduler/Scheduler.h"
 
 namespace blink {
 
 volatile int TracedTask::s_nextFlowTraceID = 0;
 
-void TracedTask::run() const
+TracedTask::TracedTask(const TraceLocation& location, const char* traceName)
+    : m_location(location)
+    , m_traceName(traceName)
+{
+    bool tracingEnabled;
+    TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink", &tracingEnabled);
+
+    if (tracingEnabled) {
+        // atomicIncrement is slow so we only do it if tracing is enabled
+        m_flowTraceID = static_cast<uint64_t>(atomicIncrement(&s_nextFlowTraceID));
+
+        TRACE_EVENT_FLOW_BEGIN2("blink", m_traceName, MANGLE(m_flowTraceID),
+        "src_file", m_location.fileName(),
+        "src_func", m_location.functionName());
+    }
+}
+
+void TracedTask::endFlowTraceEvent() const
 {
     TRACE_EVENT_FLOW_END0("blink", m_traceName, MANGLE(m_flowTraceID));
+}
 
+TracedTask::~TracedTask() { }
+
+TracedStandardTask::TracedStandardTask(const Task& task, const TraceLocation& location, const char* traceName)
+    : TracedTask(location, traceName)
+    , m_task(task) { }
+
+TracedStandardTask::~TracedStandardTask() { }
+
+void TracedStandardTask::run() const
+{
+    endFlowTraceEvent();
     TRACE_EVENT2("blink", m_traceName,
         "src_file", m_location.fileName(),
         "src_func", m_location.functionName());
@@ -20,22 +50,23 @@ void TracedTask::run() const
     m_task();
 }
 
-TracedTask::TracedTask(const Task& task, const TraceLocation& location, const char* traceName)
-    : m_task(task)
-    , m_location(location)
-    , m_traceName(traceName)
+TracedIdleTask::TracedIdleTask(const IdleTask& idleTask, const TraceLocation& location, const char* traceName)
+    : TracedTask(location, traceName)
+    , m_idleTask(idleTask)
 {
-    bool tracingEnabled;
-    TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink", &tracingEnabled);
+    ASSERT(Scheduler::shared());
+}
 
-    if (tracingEnabled) {
-        // atomicIncrement is slow so we only do it if tracing is enabled
-        m_flowTraceID = static_cast<uint64_t>(atomicIncrement(&s_nextFlowTraceID));
+TracedIdleTask::~TracedIdleTask() { }
 
-        TRACE_EVENT_FLOW_BEGIN2("blink", m_traceName, MANGLE(m_flowTraceID),
+void TracedIdleTask::run() const
+{
+    endFlowTraceEvent();
+    TRACE_EVENT2("blink", m_traceName,
         "src_file", m_location.fileName(),
         "src_func", m_location.functionName());
-    }
+
+    m_idleTask(Scheduler::shared()->currentFrameDeadlineSeconds());
 }
 
 } // namespace blink