Core - Add DependencyChecker.AssertPathAbsolute

Issue #3102

CefSharp/DependencyChecker.cs

@@ -224,5 +224,24 @@ public static void AssertAllDependenciesPresent(string locale = null, string loc
                 throw new Exception(builder.ToString());
             }
         }
+
+        /// <summary>
+        /// Throw exception if the path provided is non-asbolute
+        /// CEF now explicitly requires absolute paths
+        /// https://bitbucket.org/chromiumembedded/cef/issues/2916/not-persisting-in-local-stoage-when-using
+        /// </summary>
+        /// <param name="path">path</param>
+        /// <param name="settingName">string to appear at the start of
+        /// the exception, e.g. CefSettings.BrowserSubProcessPath</param>
+        public static void AssertPathAbsolute(string path, string settingName)
+        {
+            const string directorySeperator = "\\";
+
+            //IsPathRooted will return true for paths that start with a single slash, e.g. \programfiles
+            if (!Path.IsPathRooted(path) || Path.GetPathRoot(path).Equals(directorySeperator, StringComparison.Ordinal))
+            {
+                throw new Exception(settingName + " now requires an absolute path, the path provided is non-absolute: " + path);
+            }
+        }
     }
 }