[multiball] Deliver scene-level events on iOS 12.

Deliver AppDelegate events to SceneState. Also splits out
scene target for easier deps management in the future.

Change-Id: Ida5f9d620c7a5999cd71306a9123ef7be976b033
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1826878Reviewed-by: Mark Cogan <marq@chromium.org>
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#700216}

ios/chrome/app/BUILD.gn

@@ -227,6 +227,7 @@ source_set("app_internal") {
     "//ios/chrome/browser/ui/first_run",
     "//ios/chrome/browser/ui/history",
     "//ios/chrome/browser/ui/main",
+    "//ios/chrome/browser/ui/main:scene",
     "//ios/chrome/browser/ui/promos",
     "//ios/chrome/browser/ui/settings",
     "//ios/chrome/browser/ui/settings:settings_root",

ios/chrome/app/main_application_delegate.mm

@@ -124,6 +124,10 @@
 }
 
 - (void)applicationDidBecomeActive:(UIApplication*)application {
+  if (!IsMultiwindowSupported()) {
+    self.sceneState.activationLevel = SceneActivationLevelForegroundActive;
+  }
+
   startup_loggers::RegisterAppDidBecomeActiveTime();
   if ([_appState isInSafeMode])
     return;
@@ -133,6 +137,10 @@
 }
 
 - (void)applicationWillResignActive:(UIApplication*)application {
+  if (!IsMultiwindowSupported()) {
+    self.sceneState.activationLevel = SceneActivationLevelForegroundInactive;
+  }
+
   if ([_appState isInSafeMode])
     return;
 
@@ -142,6 +150,10 @@
 // Called when going into the background. iOS already broadcasts, so
 // stakeholders can register for it directly.
 - (void)applicationDidEnterBackground:(UIApplication*)application {
+  if (!IsMultiwindowSupported()) {
+    self.sceneState.activationLevel = SceneActivationLevelBackground;
+  }
+
   [_appState
       applicationDidEnterBackground:application
                        memoryHelper:_memoryHelper
@@ -150,6 +162,10 @@
 
 // Called when returning to the foreground.
 - (void)applicationWillEnterForeground:(UIApplication*)application {
+  if (!IsMultiwindowSupported()) {
+    self.sceneState.activationLevel = SceneActivationLevelForegroundInactive;
+  }
+
   [_appState applicationWillEnterForeground:application
                             metricsMediator:_metricsMediator
                                memoryHelper:_memoryHelper

ios/chrome/browser/ui/main/BUILD.gn

@@ -4,14 +4,9 @@
 
 import("//ios/build/chrome_build.gni")
 
-source_set("main") {
+source_set("scene") {
   configs += [ "//build/config/compiler:enable_arc" ]
   sources = [
-    "browser_interface_provider.h",
-    "browser_view_wrangler.h",
-    "browser_view_wrangler.mm",
-    "bvc_container_view_controller.h",
-    "bvc_container_view_controller.mm",
     "scene_controller.h",
     "scene_controller.mm",
     "scene_delegate.h",
@@ -19,6 +14,27 @@ source_set("main") {
     "scene_state.h",
     "scene_state.mm",
   ]
+
+  deps = [
+    ":main",
+    "//base",
+    "//ios/chrome/browser/tabs:tabs",
+    "//ios/chrome/browser/ui/commands:commands",
+    "//ios/chrome/browser/ui/tab_grid",
+  ]
+
+  libs = [ "UIKit.framework" ]
+}
+
+source_set("main") {
+  configs += [ "//build/config/compiler:enable_arc" ]
+  sources = [
+    "browser_interface_provider.h",
+    "browser_view_wrangler.h",
+    "browser_view_wrangler.mm",
+    "bvc_container_view_controller.h",
+    "bvc_container_view_controller.mm",
+  ]
   deps = [
     "//base",
     "//components/translate/core/browser",
@@ -78,6 +94,7 @@ source_set("unit_tests") {
   ]
   deps = [
     ":main",
+    ":scene",
     "//base",
     "//base/test:test_support",
     "//components/bookmarks/test",