[ios] Move IsMultipleScenesSupported to base/ios/ios_util.{h,mm}

This function is useful to check whether the device supports
having multiple scenes (which has impact on core behaviour
of the application and not just on the UI).

Move it besides other multi-window related functions.

Fix compilation when targeting iOS x86 platform caused by the
inclusion of partition_alloc header in base/memory/checked_ptr.h
even when user_partition_alloc is disabled (which is always
the case on iOS).

Bug: none
Change-Id: I31f7abb6479438176ed72467ddf9811624001911
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2640455
Auto-Submit: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
Reviewed-by: Mark Mentovai <mark@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#845666}

base/ios/ios_util.h

@@ -56,6 +56,11 @@ BASE_EXPORT bool IsMultiwindowSupported();
 // base::ios::IsMultiwindowSupported() returns true.
 BASE_EXPORT bool IsSceneStartupSupported();
 
+// Returns true iff multiple windows can be opened, i.e. when the multiwindow
+// build flag is on, the device is running on iOS 13+ and it's a compatible
+// iPad.
+BASE_EXPORT bool IsMultipleScenesSupported();
+
 }  // namespace ios
 }  // namespace base
 

base/ios/ios_util.mm

@@ -5,6 +5,8 @@
 #include "base/ios/ios_util.h"
 
 #import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
+
 #include <stddef.h>
 
 #include "base/mac/foundation_util.h"
@@ -114,5 +116,12 @@ bool IsSceneStartupSupported() {
   return cached_value;
 }
 
+bool IsMultipleScenesSupported() {
+  if (@available(iOS 13, *)) {
+    return UIApplication.sharedApplication.supportsMultipleScenes;
+  }
+  return false;
+}
+
 }  // namespace ios
 }  // namespace base

base/memory/checked_ptr.h

@@ -10,17 +10,20 @@
 
 #include <utility>
 
-#include "base/allocator/partition_allocator/address_pool_manager_bitmap.h"
-#include "base/allocator/partition_allocator/checked_ptr_support.h"
-#include "base/allocator/partition_allocator/partition_address_space.h"
-#include "base/allocator/partition_allocator/partition_alloc_forward.h"
-#include "base/allocator/partition_allocator/partition_ref_count.h"
 #include "base/check_op.h"
 #include "base/compiler_specific.h"
 #include "base/partition_alloc_buildflags.h"
 #include "build/build_config.h"
 #include "build/buildflag.h"
 
+#if BUILDFLAG(USE_PARTITION_ALLOC)
+#include "base/allocator/partition_allocator/address_pool_manager_bitmap.h"
+#include "base/allocator/partition_allocator/checked_ptr_support.h"
+#include "base/allocator/partition_allocator/partition_address_space.h"
+#include "base/allocator/partition_allocator/partition_alloc_forward.h"
+#include "base/allocator/partition_allocator/partition_ref_count.h"
+#endif
+
 #if BUILDFLAG(USE_BACKUP_REF_PTR) && !defined(OS_NACL)
 #define ENABLE_BACKUP_REF_PTR_IMPL 1
 #else

ios/chrome/browser/ui/util/multi_window_support.mm

@@ -21,8 +21,5 @@ bool IsSceneStartupSupported() {
 }
 
 bool IsMultipleScenesSupported() {
-  if (@available(iOS 13, *)) {
-    return UIApplication.sharedApplication.supportsMultipleScenes;
-  }
-  return false;
+  return base::ios::IsMultipleScenesSupported();
 }