[Mac] Touch Bar support for default browser window state

ui/base/cocoa/touch_bar_forward_declarations.h

Index: ui/base/cocoa/touch_bar_forward_declarations.h
diff --git a/ui/base/cocoa/touch_bar_forward_declarations.h b/ui/base/cocoa/touch_bar_forward_declarations.h
index 52280c23ef0bdd6ab2400edf89bc0003b5f0d78a..0e33268053145de4a44b4bb8d36ea826527b59dd 100644
--- a/ui/base/cocoa/touch_bar_forward_declarations.h
+++ b/ui/base/cocoa/touch_bar_forward_declarations.h
@@ -24,6 +24,12 @@ static const NSTouchBarItemPriority NSTouchBarItemPriorityLow = -1000;
 typedef NSString* NSTouchBarItemIdentifier;
 typedef NSString* NSTouchBarCustomizationIdentifier;
 
+static const NSTouchBarItemIdentifier NSTouchBarItemIdentifierFixedSpaceSmall =
+    @"NSTouchBarItemIdentifierFixedSpaceSmall";
+
+static const NSTouchBarItemIdentifier NSTouchBarItemIdentifierFlexibleSpace =
+    @"NSTouchBarItemIdentifierFlexibleSpace";
+
 @interface NSTouchBar : NSObject<NSCoding>
 
 - (instancetype)init NS_DESIGNATED_INITIALIZER;
@@ -104,6 +110,10 @@ typedef NSString* NSTouchBarCustomizationIdentifier;
 @protocol NSTouchBarDelegate;
 @class NSTouchBarItem;
 
+@interface NSWindow (TouchBarSDK)
+@property(strong, readonly) NSTouchBar* touchBar;
+@end
+
 #endif  // MAC_OS_X_VERSION_10_12_1
 
 #endif  // UI_BASE_COCOA_TOUCH_BAR_FORWARD_DECLARATIONS_H_