Enable V8 idle tasks.

Enables posting of idle tasks, via the blink scheduler, which notify V8 of idle
time when it can perform GC work.

BUG=421880

Review URL: https://codereview.chromium.org/639773007

git-svn-id: svn://svn.chromium.org/blink/trunk@183888 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/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"
@@ -281,6 +283,31 @@ 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) {
@@ -320,6 +347,8 @@ void V8Initializer::initializeMainThreadIfNeeded()
     v8::V8::SetFailedAccessCheckCallbackFunction(failedAccessCheckCallbackInMainThread);
     v8::V8::SetAllowCodeGenerationFromStringsCallback(codeGenerationCheckCallbackInMainThread);
 
+    postIdleGCTaskMainThread();
+
     isolate->SetEventLogger(timerTraceProfilerInMainThread);
     isolate->SetPromiseRejectCallback(promiseRejectHandlerInMainThread);
 

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.in

@@ -142,4 +142,5 @@ WebGLDraftExtensions status=experimental
 WebGLImageChromium
 WebMIDI status=test
 WebVTTRegions depends_on=Media, status=experimental
+V8IdleTasks
 XSLT status=stable

third_party/WebKit/Source/web/WebRuntimeFeatures.cpp

@@ -299,4 +299,9 @@ void WebRuntimeFeatures::setCSSViewportEnabled(bool enable)
     RuntimeEnabledFeatures::setCSSViewportEnabled(enable);
 }
 
+void WebRuntimeFeatures::enableV8IdleTasks(bool enable)
+{
+    RuntimeEnabledFeatures::setV8IdleTasksEnabled(enable);
+}
+
 } // namespace blink

third_party/WebKit/public/web/WebRuntimeFeatures.h

@@ -139,6 +139,8 @@ public:
 
     BLINK_EXPORT static void setCSSViewportEnabled(bool);
 
+    BLINK_EXPORT static void enableV8IdleTasks(bool);
+
 private:
     WebRuntimeFeatures();
 };