Add pixel to check if in between double background willEnterForeground is called (#3788)

Task/Issue URL: https://app.asana.com/0/0/1209098575913251/f

Author: jaceklyp

Core/Pixel.swift

@@ -166,6 +166,8 @@ public struct PixelParameters {
 
     public static let appState = "state"
     public static let appEvent = "event"
+
+    public static let didCallWillEnterForeground = "didCallWillEnterForeground"
 }
 
 public struct PixelValues {

Core/PixelEvent.swift

@@ -974,6 +974,8 @@ extension Pixel {
 
         // MARK: Lifecycle
         case appDidTransitionToUnexpectedState
+        case appDidConsecutivelyBackground
+
     }
 
 }
@@ -1945,6 +1947,7 @@ extension Pixel.Event {
 
         // MARK: Lifecycle
         case .appDidTransitionToUnexpectedState: return "m_debug_app-did-transition-to-unexpected-state-2"
+        case .appDidConsecutivelyBackground: return "m_debug_app-did-consecutively-background-2"
 
         }
     }

DuckDuckGo/AppDelegate.swift

@@ -67,6 +67,8 @@ protocol DDGApp {
         }
     }()
 
+    var didCallWillEnterForeground: Bool = false
+
     override init() {
         super.init()
         realDelegate.initialize()
@@ -77,6 +79,7 @@ protocol DDGApp {
     }
 
     func applicationDidBecomeActive(_ application: UIApplication) {
+        didCallWillEnterForeground = false
         realDelegate.applicationDidBecomeActive?(application)
     }
 
@@ -85,6 +88,7 @@ protocol DDGApp {
     }
 
     func applicationWillEnterForeground(_ application: UIApplication) {
+        didCallWillEnterForeground = true
         realDelegate.applicationWillEnterForeground?(application)
     }
 

DuckDuckGo/AppLifecycle/AppStateTransitions.swift

@@ -104,6 +104,12 @@ extension Background {
             urlToOpen = url
             return self
         case .backgrounding:
+            if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
+                Pixel.fire(pixel: .appDidConsecutivelyBackground, withAdditionalParameters: [
+                    PixelParameters.didCallWillEnterForeground: appDelegate.didCallWillEnterForeground.description
+                ])
+                appDelegate.didCallWillEnterForeground = false
+            }
             run()
             return self
         case .handleShortcutItem(let shortcutItem):