void InspectorTimelineAgent::internalStart(const int* maxCallStackDepth)
{
    if (m_enabled)
        return;

    if (maxCallStackDepth && *maxCallStackDepth > 0)
        m_maxCallStackDepth = *maxCallStackDepth;
    else
        m_maxCallStackDepth = 5;

    m_instrumentingAgents.setInspectorTimelineAgent(this);

    if (m_scriptDebugServer)
        m_scriptDebugServer->addListener(this);

    m_enabled = true;

    // FIXME: Abstract away platform-specific code once https://bugs.webkit.org/show_bug.cgi?id=142748 is fixed.

#if PLATFORM(COCOA)
    m_frameStartObserver = RunLoopObserver::create(0, [this]() {
        if (!m_enabled || m_scriptDebugServer->isPaused())
            return;

        if (!m_runLoopNestingLevel)
            pushCurrentRecord(InspectorObject::create(), TimelineRecordType::RenderingFrame, false, nullptr);
        m_runLoopNestingLevel++;
    });

    m_frameStopObserver = RunLoopObserver::create(frameStopRunLoopOrder, [this]() {
        if (!m_enabled || m_scriptDebugServer->isPaused())
            return;

        ASSERT(m_runLoopNestingLevel > 0);
        m_runLoopNestingLevel--;
        if (m_runLoopNestingLevel)
            return;

        if (m_startedComposite)
            didComposite();

        didCompleteCurrentRecord(TimelineRecordType::RenderingFrame);
    });

    m_frameStartObserver->schedule(currentRunLoop(), kCFRunLoopEntry | kCFRunLoopAfterWaiting);
    m_frameStopObserver->schedule(currentRunLoop(), kCFRunLoopExit | kCFRunLoopBeforeWaiting);

    // Create a runloop record and increment the runloop nesting level, to capture the current turn of the main runloop
    // (which is the outer runloop if recording started while paused in the debugger).
    pushCurrentRecord(InspectorObject::create(), TimelineRecordType::RenderingFrame, false, nullptr);

    m_runLoopNestingLevel = 1;
#endif

    m_frontendDispatcher->recordingStarted(timestamp());
}

void InspectorTimelineAgent::willCallFunction(const String& scriptName, int scriptLine, Frame* frame)
{
    pushCurrentRecord(TimelineRecordFactory::createFunctionCallData(scriptName, scriptLine), TimelineRecordType::FunctionCall, true, frame);

    if (frame && !m_callStackDepth)
        startProfiling(frame, ASCIILiteral("Timeline FunctionCall"), m_instrumentingAgents.inspectorEnvironment().executionStopwatch());

    ++m_callStackDepth;
}

void InspectorTimelineAgent::willEvaluateScript(const String& url, int lineNumber, Frame* frame)
{
    pushCurrentRecord(TimelineRecordFactory::createEvaluateScriptData(url, lineNumber), TimelineRecordType::EvaluateScript, true, frame);

    if (frame && !m_recordingProfile) {
        m_recordingProfile = true;
        startProfiling(frame, ASCIILiteral("Timeline EvaluateScript"));
    }
}

void InspectorTimelineAgent::willComposite(Frame& frame)
{
    ASSERT(!m_startedComposite);
    pushCurrentRecord(InspectorObject::create(), TimelineRecordType::Composite, true, &frame);
    m_startedComposite = true;
}

void InspectorTimelineAgent::willResizeImage(bool shouldCache)
{
    pushCurrentRecord(TimelineRecordFactory::createResizeImageData(shouldCache), TimelineRecordType::ResizeImage, true, 0);
}