Enable V8 idle tasks.

Source/bindings/core/v8/V8Initializer.cpp

Index: Source/bindings/core/v8/V8Initializer.cpp
diff --git a/Source/bindings/core/v8/V8Initializer.cpp b/Source/bindings/core/v8/V8Initializer.cpp
index 3e3157b30eea1a0a7b7052b561545c2c3e07bf16..f8441c25f57e8cfa6a7c3a786e907f28afed8460 100644
--- a/Source/bindings/core/v8/V8Initializer.cpp
+++ b/Source/bindings/core/v8/V8Initializer.cpp
@@ -50,7 +50,9 @@
 #include "core/inspector/ScriptArguments.h"
 #include "core/inspector/ScriptCallStack.h"
 #include "platform/EventDispatchForbiddenScope.h"
+#include "platform/RuntimeEnabledFeatures.h"
 #include "platform/TraceEvent.h"
+#include "platform/scheduler/Scheduler.h"
 #include "public/platform/Platform.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/WTFString.h"
@@ -253,6 +255,31 @@ static bool codeGenerationCheckCallbackInMainThread(v8::Local<v8::Context> conte
     return false;
 }
 
+static void idleGCTaskInMainThread(double deadlineSeconds);
+
+static void postIdleGCTaskMainThread()
+{
+    if (RuntimeEnabledFeatures::v8IdleTasksEnabled()) {
+        Scheduler* scheduler = Scheduler::shared();
+        if (scheduler)
+            scheduler->postIdleTask(FROM_HERE, WTF::bind<double>(idleGCTaskInMainThread));
+    }
+}
+
+static void idleGCTaskInMainThread(double deadlineSeconds)
+{
+    ASSERT(isMainThread());
+    ASSERT(RuntimeEnabledFeatures::v8IdleTasksEnabled());
+    v8::Isolate* isolate = v8::Isolate::GetCurrent();
+    // FIXME: Change V8's API to take a deadline - http://crbug.com/417668
+    double idleTimeInSeconds = deadlineSeconds - Platform::current()->monotonicallyIncreasingTime();
+    int idleTimeInMillis = static_cast<int>(idleTimeInSeconds * 1000);
+    if (idleTimeInMillis > 0)
+        isolate->IdleNotification(idleTimeInMillis);
+    // FIXME: only repost if there is more work to do.
+    postIdleGCTaskMainThread();
+}
+
 static void timerTraceProfilerInMainThread(const char* name, int status)
 {
     if (!status) {
@@ -292,6 +319,8 @@ void V8Initializer::initializeMainThreadIfNeeded()
     v8::V8::SetFailedAccessCheckCallbackFunction(failedAccessCheckCallbackInMainThread);
     v8::V8::SetAllowCodeGenerationFromStringsCallback(codeGenerationCheckCallbackInMainThread);
 
+    postIdleGCTaskMainThread();
+
     isolate->SetEventLogger(timerTraceProfilerInMainThread);
     isolate->SetPromiseRejectCallback(promiseRejectHandlerInMainThread);