Fixes 3713

Moved the UmbracoApplicationBase from Core to Web
Moved the WebProfiler from Core to Web
Removed UmbracoApplicationBase from the CoreRuntime, it's still in the WebRuntime (and registered there in DI)

src/Umbraco.Web/Logging/WebProfiler.cs

@@ -0,0 +1,108 @@
+using System;
+using System.Threading;
+using System.Web;
+using StackExchange.Profiling;
+using StackExchange.Profiling.SqlFormatters;
+using Umbraco.Core;
+using Umbraco.Core.Logging;
+
+namespace Umbraco.Web.Logging
+{
+    /// <summary>
+    /// Implements <see cref="IProfiler"/> by using the MiniProfiler framework.
+    /// </summary>
+    internal class WebProfiler : IProfiler
+    {
+        private const string BootRequestItemKey = "Umbraco.Core.Logging.WebProfiler__isBootRequest";
+        private readonly WebProfilerProvider _provider;
+        private int _first;
+
+        public WebProfiler()
+        {
+            // create our own provider, which can provide a profiler even during boot
+            _provider = new WebProfilerProvider();
+
+            // settings
+            MiniProfiler.Settings.SqlFormatter = new SqlServerFormatter();
+            MiniProfiler.Settings.StackMaxLength = 5000;
+            MiniProfiler.Settings.ProfilerProvider = _provider;
+        }
+
+        public void UmbracoApplicationBeginRequest(object sender, EventArgs e)
+        {
+            // if this is the first request, notify our own provider that this request is the boot request
+            var first = Interlocked.Exchange(ref _first, 1) == 0;
+            if (first)
+            {
+                _provider.BeginBootRequest();
+                ((HttpApplication) sender).Context.Items[BootRequestItemKey] = true;
+                // and no need to start anything, profiler is already there
+            }
+            // else start a profiler, the normal way
+            else if (ShouldProfile(sender))
+                Start();
+        }
+
+        public void UmbracoApplicationEndRequest(object sender, EventArgs e)
+        {
+            // if this is the boot request, or if we should profile this request, stop
+            // (the boot request is always profiled, no matter what)
+            var isBootRequest = ((HttpApplication) sender).Context.Items[BootRequestItemKey] != null; // fixme perfs
+            if (isBootRequest)
+                _provider.EndBootRequest();
+            if (isBootRequest || ShouldProfile(sender))
+                Stop();
+        }
+
+        private static bool ShouldProfile(object sender)
+        {
+            var request = TryGetRequest(sender);
+            if (request.Success == false) return false;
+
+            if (request.Result.Url.IsClientSideRequest()) return false;
+            if (bool.TryParse(request.Result.QueryString["umbDebug"], out var umbDebug)) return umbDebug;
+            if (bool.TryParse(request.Result.Headers["X-UMB-DEBUG"], out var xUmbDebug)) return xUmbDebug;
+            return false;
+        }
+
+        /// <inheritdoc/>
+        public string Render()
+        {
+            return MiniProfiler.RenderIncludes(RenderPosition.Right).ToString();
+        }
+
+        /// <inheritdoc/>
+        public IDisposable Step(string name)
+        {
+            return MiniProfiler.Current.Step(name);
+        }
+
+        /// <inheritdoc/>
+        public void Start()
+        {
+            MiniProfiler.Start();
+        }
+
+        /// <inheritdoc/>
+        public void Stop(bool discardResults = false)
+        {
+            MiniProfiler.Stop(discardResults);
+        }
+
+        private static Attempt<HttpRequestBase> TryGetRequest(object sender)
+        {
+            var app = sender as HttpApplication;
+            if (app == null) return Attempt<HttpRequestBase>.Fail();
+
+            try
+            {
+                var req = app.Request;
+                return Attempt<HttpRequestBase>.Succeed(new HttpRequestWrapper(req));
+            }
+            catch (HttpException ex)
+            {
+                return Attempt<HttpRequestBase>.Fail(ex);
+            }
+        }
+    }
+}