[multiball] Opening new window should not restore last session.

Assigns IDs semi-randomly to created scenes and restores the session
from a given session ID into a scene.
This fixes a bug where opening a new window would restore the previous
session from the first window.
However, a permanent solution here would be to actually implement
session restoration that is not based on non-persistent integer
window IDs.

Bug: 1069747
Change-Id: I4a5352d56f4a7d506ff618944b9868c688a5b612
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144274
Commit-Queue: Stepan Khapugin <stkhapugin@chromium.org>
Commit-Queue: Mark Cogan <marq@chromium.org>
Auto-Submit: Stepan Khapugin <stkhapugin@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758205}

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

@@ -129,6 +129,7 @@ source_set("main") {
     "//ios/chrome/browser/ui/recent_tabs",
     "//ios/chrome/browser/ui/snackbar",
     "//ios/chrome/browser/ui/translate:legacy_translate",
+    "//ios/chrome/browser/ui/util:multiwindow_util",
     "//ios/chrome/browser/url_loading",
     "//ios/chrome/browser/web",
     "//ios/chrome/browser/web:tab_helper_delegates",

ios/chrome/browser/ui/main/browser_view_wrangler.h

@@ -43,6 +43,11 @@ NSString* kIncognitoCurrentKey = @"IncognitoActive";
 
 - (instancetype)init NS_UNAVAILABLE;
 
+// Window ID. Only used in multiwindow. Temporary solution for session
+// restoration in multiwindow.
+// TODO(crbug.com/1069762): remove this.
+@property(nonatomic, assign) NSUInteger windowID;
+
 // Creates the main Browser used by the receiver, using the browser state
 // and tab model observer it was configured with. The main interface is then
 // created; until this method is called, the main and incognito interfaces will

ios/chrome/browser/ui/main/browser_view_wrangler.mm

@@ -25,6 +25,7 @@
 #import "ios/chrome/browser/ui/commands/application_commands.h"
 #import "ios/chrome/browser/ui/commands/browsing_data_commands.h"
 #import "ios/chrome/browser/ui/commands/command_dispatcher.h"
+#import "ios/chrome/browser/ui/util/multi_window_support.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
@@ -408,10 +409,18 @@
       browser->GetBrowserState()->GetStatePath().AsUTF8Unsafe());
   SessionIOS* session =
       [[SessionServiceIOS sharedService] loadSessionFromDirectory:statePath];
-  if (session) {
-    DCHECK_EQ(session.sessionWindows.count, 1u);
-    sessionWindow = session.sessionWindows[0];
+  if (IsMultiwindowSupported()) {
+    if (session && session.sessionWindows.count > self.windowID) {
+      sessionWindow = session.sessionWindows[self.windowID];
+    }
+
+  } else {
+    if (session) {
+      DCHECK_EQ(session.sessionWindows.count, 1u);
+      sessionWindow = session.sessionWindows[0];
+    }
   }
+
   SessionRestorationBrowserAgent::FromBrowser(browser)->RestoreSessionWindow(
       sessionWindow);
 }

ios/chrome/browser/ui/main/scene_controller.mm

@@ -306,6 +306,8 @@ const NSTimeInterval kDisplayPromoDelay = 0.1;
        applicationCommandEndpoint:self
       browsingDataCommandEndpoint:self.mainController];
 
+  self.browserViewWrangler.windowID = self.sceneState.windowID;
+
   // Ensure the main browser is created. This also creates the BVC.
   [self.browserViewWrangler createMainBrowser];
 

ios/chrome/browser/ui/main/scene_state.h

@@ -45,6 +45,10 @@ typedef NS_ENUM(NSUInteger, SceneActivationLevel) {
 // The current activation level.
 @property(nonatomic, assign) SceneActivationLevel activationLevel;
 
+// Window ID, used for restoration.
+// TODO(crbug.com/1069762): remove this.
+@property(nonatomic, assign, readonly) NSUInteger windowID;
+
 // Window for the associated scene, if any.
 @property(nonatomic, strong) UIWindow* window;
 

ios/chrome/browser/ui/main/scene_state.mm

@@ -30,12 +30,16 @@
 
 @implementation SceneState
 @synthesize window = _window;
+@synthesize windowID = _windowID;
 
 - (instancetype)init {
   self = [super init];
   if (self) {
     _observers = [SceneStateObserverList
         observersWithProtocol:@protocol(SceneStateObserver)];
+    if (@available(iOS 13, *)) {
+      _windowID = UIApplication.sharedApplication.connectedScenes.count - 1;
+    }
   }
   return self;
 }
@@ -52,6 +56,14 @@
 
 #pragma mark - Setters & Getters.
 
+- (NSUInteger)windowID {
+  if (IsMultiwindowSupported()) {
+    return _windowID;
+  } else {
+    return 0;
+  }
+}
+
 - (void)setWindow:(UIWindow*)window {
   if (IsMultiwindowSupported()) {
     // No need to set anything, instead the getter is backed by scene.windows