Update from https://crrev.com/328418

base/mac/sdk_forward_declarations.h

Index: base/mac/sdk_forward_declarations.h
diff --git a/base/mac/sdk_forward_declarations.h b/base/mac/sdk_forward_declarations.h
index 25d937e0120a255bd66f62fa4c549e4fde253879..d7be320990d68bff35d855c80c8128665f898ac2 100644
--- a/base/mac/sdk_forward_declarations.h
+++ b/base/mac/sdk_forward_declarations.h
@@ -18,16 +18,91 @@
 
 #include "base/base_export.h"
 
+// ----------------------------------------------------------------------------
+// Either define or forward declare classes only available in OSX 10.7+.
+// ----------------------------------------------------------------------------
+
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
+
+@interface CWChannel : NSObject
+@end
+
+@interface CBPeripheral : NSObject
+@end
+
+@interface CBCentralManager : NSObject
+@end
+
+@interface CBUUID : NSObject
+@end
+
+#else
+
+@class CWChannel;
+@class CBPeripheral;
+@class CBCentralManager;
+@class CBUUID;
+
+#endif  // MAC_OS_X_VERSION_10_7
+
+#if !defined(MAC_OS_X_VERSION_10_8) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_8
+
+@interface NSUUID : NSObject
+@end
+
+#else
+
+@class NSUUID;
+
+#endif  // MAC_OS_X_VERSION_10_8
+
+#if !defined(MAC_OS_X_VERSION_10_9) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_9
+
+// NSProgress is public API in 10.9, but a version of it exists and is usable
+// in 10.8.
+@interface NSProgress : NSObject
+@end
+
+@interface NSAppearance : NSObject
+@end
+
+#else
+
+@class NSProgress;
+@class NSAppearance;
+
+#endif  // MAC_OS_X_VERSION_10_9
+
+#if !defined(MAC_OS_X_VERSION_10_10) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_10
+
+@interface NSUserActivity : NSObject
+@end
+
+#else
+
+@class NSUserActivity;
+
+#endif  // MAC_OS_X_VERSION_10_10
+
+// ----------------------------------------------------------------------------
+// Define typedefs, enums, and protocols not available in the version of the
+// OSX SDK being compiled against.
+// ----------------------------------------------------------------------------
+
 #if !defined(MAC_OS_X_VERSION_10_7) || \
     MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_7
 
 enum {
-  NSEventPhaseNone        = 0, // event not associated with a phase.
-  NSEventPhaseBegan       = 0x1 << 0,
-  NSEventPhaseStationary  = 0x1 << 1,
-  NSEventPhaseChanged     = 0x1 << 2,
-  NSEventPhaseEnded       = 0x1 << 3,
-  NSEventPhaseCancelled   = 0x1 << 4
+  NSEventPhaseNone = 0,  // event not associated with a phase.
+  NSEventPhaseBegan = 0x1 << 0,
+  NSEventPhaseStationary = 0x1 << 1,
+  NSEventPhaseChanged = 0x1 << 2,
+  NSEventPhaseEnded = 0x1 << 3,
+  NSEventPhaseCancelled = 0x1 << 4
 };
 typedef NSUInteger NSEventPhase;
 
@@ -65,9 +140,139 @@ enum {
 };
 typedef NSUInteger NSWindowButton;
 
+enum CWChannelBand {
+  kCWChannelBandUnknown = 0,
+  kCWChannelBand2GHz = 1,
+  kCWChannelBand5GHz = 2,
+};
+
+enum {
+  kCWSecurityNone = 0,
+  kCWSecurityWEP = 1,
+  kCWSecurityWPAPersonal = 2,
+  kCWSecurityWPAPersonalMixed = 3,
+  kCWSecurityWPA2Personal = 4,
+  kCWSecurityPersonal = 5,
+  kCWSecurityDynamicWEP = 6,
+  kCWSecurityWPAEnterprise = 7,
+  kCWSecurityWPAEnterpriseMixed = 8,
+  kCWSecurityWPA2Enterprise = 9,
+  kCWSecurityEnterprise = 10,
+  kCWSecurityUnknown = NSIntegerMax,
+};
+
+typedef NSInteger CWSecurity;
+
+enum {
+  kBluetoothFeatureLESupportedController = (1 << 6L),
+};
+
+@protocol IOBluetoothDeviceInquiryDelegate
+- (void)deviceInquiryStarted:(IOBluetoothDeviceInquiry*)sender;
+- (void)deviceInquiryDeviceFound:(IOBluetoothDeviceInquiry*)sender
+                          device:(IOBluetoothDevice*)device;
+- (void)deviceInquiryComplete:(IOBluetoothDeviceInquiry*)sender
+                        error:(IOReturn)error
+                      aborted:(BOOL)aborted;
+@end
+
+@protocol NSWindowDelegateFullScreenAdditions
+- (void)windowDidFailToEnterFullScreen:(NSWindow*)window;
+- (void)windowDidFailToExitFullScreen:(NSWindow*)window;
+@end
+
+enum {
+  CBPeripheralStateDisconnected = 0,
+  CBPeripheralStateConnecting,
+  CBPeripheralStateConnected,
+};
+typedef NSInteger CBPeripheralState;
+
+enum {
+  CBCentralManagerStateUnknown = 0,
+  CBCentralManagerStateResetting,
+  CBCentralManagerStateUnsupported,
+  CBCentralManagerStateUnauthorized,
+  CBCentralManagerStatePoweredOff,
+  CBCentralManagerStatePoweredOn,
+};
+typedef NSInteger CBCentralManagerState;
+
+@protocol CBCentralManagerDelegate;
+
+@protocol CBCentralManagerDelegate<NSObject>
+- (void)centralManagerDidUpdateState:(CBCentralManager*)central;
+- (void)centralManager:(CBCentralManager*)central
+    didDiscoverPeripheral:(CBPeripheral*)peripheral
+        advertisementData:(NSDictionary*)advertisementData
+                     RSSI:(NSNumber*)RSSI;
+@end
+
+#endif  // MAC_OS_X_VERSION_10_7
+
+#if !defined(MAC_OS_X_VERSION_10_8) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_8
+
+enum { NSEventPhaseMayBegin = 0x1 << 5 };
+
+#endif  // MAC_OS_X_VERSION_10_8
+
+#if !defined(MAC_OS_X_VERSION_10_9) || \
+    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_9
+
+enum {
+  NSWindowOcclusionStateVisible = 1UL << 1,
+};
+typedef NSUInteger NSWindowOcclusionState;
+
+enum { NSWorkspaceLaunchWithErrorPresentation = 0x00000040 };
+
+#endif  // MAC_OS_X_VERSION_10_9
+
+// ----------------------------------------------------------------------------
+// Define NSStrings only available in newer versions of the OSX SDK to force
+// them to be statically linked.
+// ----------------------------------------------------------------------------
+
+extern "C" {
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7
+BASE_EXPORT extern NSString* const NSWindowWillEnterFullScreenNotification;
+BASE_EXPORT extern NSString* const NSWindowWillExitFullScreenNotification;
+BASE_EXPORT extern NSString* const NSWindowDidEnterFullScreenNotification;
+BASE_EXPORT extern NSString* const NSWindowDidExitFullScreenNotification;
+BASE_EXPORT extern NSString* const
+    NSWindowDidChangeBackingPropertiesNotification;
+BASE_EXPORT extern NSString* const CBAdvertisementDataServiceDataKey;
+#endif  // MAC_OS_X_VERSION_10_7
+
+#if !defined(MAC_OS_X_VERSION_10_9) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_9
+BASE_EXPORT extern NSString* const NSWindowDidChangeOcclusionStateNotification;
+BASE_EXPORT extern NSString* const CBAdvertisementDataIsConnectable;
+#endif  // MAC_OS_X_VERSION_10_9
+
+#if !defined(MAC_OS_X_VERSION_10_10) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_10
+BASE_EXPORT extern NSString* const NSUserActivityTypeBrowsingWeb;
+BASE_EXPORT extern NSString* const NSAppearanceNameVibrantDark;
+#endif  // MAC_OS_X_VERSION_10_10
+}  // extern "C"
+
+// ----------------------------------------------------------------------------
+// If compiling against an older version of the OSX SDK, declare functions that
+// are available in newer versions of the OSX SDK. If compiling against a newer
+// version of the OSX SDK, redeclare those same functions to suppress
+// -Wpartial-availability warnings.
+// ----------------------------------------------------------------------------
+
+// Once Chrome no longer supports OSX 10.6, everything within this preprocessor
+// block can be removed.
+#if !defined(MAC_OS_X_VERSION_10_7) || \
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_7
+
 @interface NSEvent (LionSDK)
 + (BOOL)isSwipeTrackingFromScrollEventsEnabled;
-
 - (NSEventPhase)momentumPhase;
 - (NSEventPhase)phase;
 - (BOOL)hasPreciseScrollingDeltas;
@@ -79,10 +284,8 @@ typedef NSUInteger NSWindowButton;
                       usingHandler:(void (^)(CGFloat gestureAmount,
                                              NSEventPhase phase,
                                              BOOL isComplete,
-                                             BOOL *stop))trackingHandler;
-
+                                             BOOL* stop))trackingHandler;
 - (BOOL)isDirectionInvertedFromDevice;
-
 @end
 
 @interface NSApplication (LionSDK)
@@ -113,9 +316,9 @@ typedef NSUInteger NSWindowButton;
 @end
 
 @interface NSAnimationContext (LionSDK)
-+ (void)runAnimationGroup:(void (^)(NSAnimationContext *context))changes
++ (void)runAnimationGroup:(void (^)(NSAnimationContext* context))changes
         completionHandler:(void (^)(void))completionHandler;
-@property(copy) void(^completionHandler)(void);
+@property(copy) void (^completionHandler)(void);
 @end
 
 @interface NSView (LionSDK)
@@ -139,37 +342,13 @@ typedef NSUInteger NSWindowButton;
 - (BOOL)associateToNetwork:(CWNetwork*)network
                   password:(NSString*)password
                      error:(NSError**)error;
-- (NSSet*)scanForNetworksWithName:(NSString*)networkName
-                            error:(NSError**)error;
+- (NSSet*)scanForNetworksWithName:(NSString*)networkName error:(NSError**)error;
 @end
 
-enum CWChannelBand {
-  kCWChannelBandUnknown = 0,
-  kCWChannelBand2GHz = 1,
-  kCWChannelBand5GHz = 2,
-};
-
-@interface CWChannel : NSObject
+@interface CWChannel (LionSDK)
 @property(readonly) CWChannelBand channelBand;
 @end
 
-enum {
-   kCWSecurityNone = 0,
-   kCWSecurityWEP = 1,
-   kCWSecurityWPAPersonal = 2,
-   kCWSecurityWPAPersonalMixed = 3,
-   kCWSecurityWPA2Personal = 4,
-   kCWSecurityPersonal = 5,
-   kCWSecurityDynamicWEP = 6,
-   kCWSecurityWPAEnterprise = 7,
-   kCWSecurityWPAEnterpriseMixed = 8,
-   kCWSecurityWPA2Enterprise = 9,
-   kCWSecurityEnterprise = 10,
-   kCWSecurityUnknown = NSIntegerMax,
-};
-
-typedef NSInteger CWSecurity;
-
 @interface CWNetwork (LionSDK)
 @property(readonly) CWChannel* wlanChannel;
 @property(readonly) NSInteger rssiValue;
@@ -181,19 +360,6 @@ typedef NSInteger CWSecurity;
 - (BluetoothHCIPowerState)powerState;
 @end
 
-enum {
-  kBluetoothFeatureLESupportedController = (1 << 6L),
-};
-
-@protocol IOBluetoothDeviceInquiryDelegate
-- (void)deviceInquiryStarted:(IOBluetoothDeviceInquiry*)sender;
-- (void)deviceInquiryDeviceFound:(IOBluetoothDeviceInquiry*)sender
-                          device:(IOBluetoothDevice*)device;
-- (void)deviceInquiryComplete:(IOBluetoothDeviceInquiry*)sender
-                        error:(IOReturn)error
-                      aborted:(BOOL)aborted;
-@end
-
 @interface IOBluetoothL2CAPChannel (LionSDK)
 @property(readonly) BluetoothL2CAPMTU outgoingMTU;
 @end
@@ -207,46 +373,13 @@ enum {
 - (IOReturn)performSDPQuery:(id)target uuids:(NSArray*)uuids;
 @end
 
-BASE_EXPORT extern "C" NSString* const NSWindowWillEnterFullScreenNotification;
-BASE_EXPORT extern "C" NSString* const NSWindowWillExitFullScreenNotification;
-BASE_EXPORT extern "C" NSString* const NSWindowDidEnterFullScreenNotification;
-BASE_EXPORT extern "C" NSString* const NSWindowDidExitFullScreenNotification;
-BASE_EXPORT extern "C" NSString* const
-    NSWindowDidChangeBackingPropertiesNotification;
-
-@protocol NSWindowDelegateFullScreenAdditions
-- (void)windowDidFailToEnterFullScreen:(NSWindow*)window;
-- (void)windowDidFailToExitFullScreen:(NSWindow*)window;
-@end
-
-BASE_EXPORT extern "C" NSString* const CBAdvertisementDataServiceDataKey;
-
-enum {
-  CBPeripheralStateDisconnected = 0,
-  CBPeripheralStateConnecting,
-  CBPeripheralStateConnected,
-};
-typedef NSInteger CBPeripheralState;
-
-@interface CBPeripheral : NSObject
+@interface CBPeripheral (LionSDK)
 @property(readonly, nonatomic) CFUUIDRef UUID;
 @property(retain, readonly) NSString* name;
 @property(readonly) BOOL isConnected;
 @end
 
-enum {
-  CBCentralManagerStateUnknown = 0,
-  CBCentralManagerStateResetting,
-  CBCentralManagerStateUnsupported,
-  CBCentralManagerStateUnauthorized,
-  CBCentralManagerStatePoweredOff,
-  CBCentralManagerStatePoweredOn,
-};
-typedef NSInteger CBCentralManagerState;
-
-@protocol CBCentralManagerDelegate;
-
-@interface CBCentralManager : NSObject
+@interface CBCentralManager (LionSDK)
 @property(readonly) CBCentralManagerState state;
 - (id)initWithDelegate:(id<CBCentralManagerDelegate>)delegate
                  queue:(dispatch_queue_t)queue;
@@ -255,33 +388,23 @@ typedef NSInteger CBCentralManagerState;
 - (void)stopScan;
 @end
 
-@protocol CBCentralManagerDelegate<NSObject>
-- (void)centralManagerDidUpdateState:(CBCentralManager*)central;
-- (void)centralManager:(CBCentralManager*)central
-    didDiscoverPeripheral:(CBPeripheral*)peripheral
-        advertisementData:(NSDictionary*)advertisementData
-                     RSSI:(NSNumber*)RSSI;
-@end
-
-@interface CBUUID : NSObject
+@interface CBUUID (LionSDK)
 @property(nonatomic, readonly) NSData* data;
 + (CBUUID*)UUIDWithString:(NSString*)theString;
 @end
 
 #endif  // MAC_OS_X_VERSION_10_7
 
+// Once Chrome no longer supports OSX 10.7, everything within this preprocessor
+// block can be removed.
 #if !defined(MAC_OS_X_VERSION_10_8) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_8
-
-enum {
-  NSEventPhaseMayBegin    = 0x1 << 5
-};
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_8
 
 @interface NSColor (MountainLionSDK)
 - (CGColorRef)CGColor;
 @end
 
-@interface NSUUID : NSObject
+@interface NSUUID (MountainLionSDK)
 - (NSString*)UUIDString;
 @end
 
@@ -291,36 +414,34 @@ enum {
 
 #endif  // MAC_OS_X_VERSION_10_8
 
-
+// Once Chrome no longer supports OSX 10.8, everything within this preprocessor
+// block can be removed.
 #if !defined(MAC_OS_X_VERSION_10_9) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_9
-
-// NSProgress is public API in 10.9, but a version of it exists and is usable
-// in 10.8.
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_9
 
-@interface NSProgress : NSObject
+@interface NSProgress (MavericksSDK)
 
 - (instancetype)initWithParent:(NSProgress*)parentProgressOrNil
                       userInfo:(NSDictionary*)userInfoOrNil;
-@property (copy) NSString* kind;
+@property(copy) NSString* kind;
 
 @property int64_t totalUnitCount;
 @property int64_t completedUnitCount;
 
-@property (getter=isCancellable) BOOL cancellable;
-@property (getter=isPausable) BOOL pausable;
-@property (readonly, getter=isCancelled) BOOL cancelled;
-@property (readonly, getter=isPaused) BOOL paused;
-@property (copy) void (^cancellationHandler)(void);
-@property (copy) void (^pausingHandler)(void);
+@property(getter=isCancellable) BOOL cancellable;
+@property(getter=isPausable) BOOL pausable;
+@property(readonly, getter=isCancelled) BOOL cancelled;
+@property(readonly, getter=isPaused) BOOL paused;
+@property(copy) void (^cancellationHandler)(void);
+@property(copy) void (^pausingHandler)(void);
 - (void)cancel;
 - (void)pause;
 
 - (void)setUserInfoObject:(id)objectOrNil forKey:(NSString*)key;
 - (NSDictionary*)userInfo;
 
-@property (readonly, getter=isIndeterminate) BOOL indeterminate;
-@property (readonly) double fractionCompleted;
+@property(readonly, getter=isIndeterminate) BOOL indeterminate;
+@property(readonly) double fractionCompleted;
 
 - (void)publish;
 - (void)unpublish;
@@ -331,72 +452,35 @@ enum {
 + (BOOL)screensHaveSeparateSpaces;
 @end
 
-// NSAppearance is a new class in the 10.9 SDK. New classes cannot be
-// forward-declared because they also require an @implementation, which would
-// produce conflicting linkage. Instead, just declare the necessary pieces of
-// the interface as a protocol, and treat objects of this type as id.
-@protocol CrNSAppearance<NSObject>
-+ (id<NSObject>)appearanceNamed:(NSString*)name;
-@end
-
 @interface NSView (MavericksSDK)
 - (void)setCanDrawSubviewsIntoLayer:(BOOL)flag;
-- (id<CrNSAppearance>)effectiveAppearance;
+- (NSAppearance*)effectiveAppearance;
 @end
 
-enum {
-  NSWindowOcclusionStateVisible = 1UL << 1,
-};
-typedef NSUInteger NSWindowOcclusionState;
-
 @interface NSWindow (MavericksSDK)
 - (NSWindowOcclusionState)occlusionState;
 @end
 
-
-BASE_EXPORT extern "C" NSString* const
-    NSWindowDidChangeOcclusionStateNotification;
-
-enum {
-  NSWorkspaceLaunchWithErrorPresentation = 0x00000040
-};
+@interface NSAppearance (MavericksSDK)
++ (id<NSObject>)appearanceNamed:(NSString*)name;
+@end
 
 @interface CBPeripheral (MavericksSDK)
 @property(readonly, nonatomic) NSUUID* identifier;
 @end
 
-BASE_EXPORT extern "C" NSString* const CBAdvertisementDataIsConnectable;
-
-#else  // !MAC_OS_X_VERSION_10_9
-
-typedef enum {
-   kCWSecurityModeOpen = 0,
-   kCWSecurityModeWEP,
-   kCWSecurityModeWPA_PSK,
-   kCWSecurityModeWPA2_PSK,
-   kCWSecurityModeWPA_Enterprise,
-   kCWSecurityModeWPA2_Enterprise,
-   kCWSecurityModeWPS,
-   kCWSecurityModeDynamicWEP
-} CWSecurityMode;
-
-@interface CWNetwork (SnowLeopardSDK)
-@property(readonly) NSNumber* rssi;
-@property(readonly) NSNumber* securityMode;
-@end
-
-BASE_EXPORT extern "C" NSString* const kCWSSIDDidChangeNotification;
-
 #endif  // MAC_OS_X_VERSION_10_9
 
+// Once Chrome no longer supports OSX 10.9, everything within this preprocessor
+// block can be removed.
 #if !defined(MAC_OS_X_VERSION_10_10) || \
-    MAC_OS_X_VERSION_MAX_ALLOWED < MAC_OS_X_VERSION_10_10
+    MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_10
 
-@interface NSUserActivity : NSObject
+@interface NSUserActivity (YosemiteSDK)
 
-@property (readonly, copy) NSString* activityType;
-@property (copy) NSDictionary* userInfo;
-@property (copy) NSURL* webpageURL;
+@property(readonly, copy) NSString* activityType;
+@property(copy) NSDictionary* userInfo;
+@property(copy) NSURL* webpageURL;
 
 - (instancetype)initWithActivityType:(NSString*)activityType;
 - (void)becomeCurrent;
@@ -404,14 +488,48 @@ BASE_EXPORT extern "C" NSString* const kCWSSIDDidChangeNotification;
 
 @end
 
-BASE_EXPORT extern "C" NSString* const NSUserActivityTypeBrowsingWeb;
-
-BASE_EXPORT extern "C" NSString* const NSAppearanceNameVibrantDark;
-
 @interface CBUUID (YosemiteSDK)
 - (NSString*)UUIDString;
 @end
 
 #endif  // MAC_OS_X_VERSION_10_10
 
+// ----------------------------------------------------------------------------
+// Chrome uses -[CWNetwork securityMode] and -[CWNetwork rssi] on OSX 10.6. The
+// former method relies on the enum CWSecurityMode which was removed in the OSX
+// 10.9 SDK. In order for Chrome to compile against an OSX 10.9+ SDK, Chrome
+// must define this enum. Chrome must also declare these methods.
+//
+// These declarations and definitions will not be necessary once Chrome no
+// longer runs on OSX 10.6.
+// ----------------------------------------------------------------------------
+#if defined(MAC_OS_X_VERSION_10_9) && \
+    MAC_OS_X_VERSION_MIN_REQUIRED <= MAC_OS_X_VERSION_10_6
+typedef enum {
+  kCWSecurityModeOpen = 0,
+  kCWSecurityModeWEP,
+  kCWSecurityModeWPA_PSK,
+  kCWSecurityModeWPA2_PSK,
+  kCWSecurityModeWPA_Enterprise,
+  kCWSecurityModeWPA2_Enterprise,
+  kCWSecurityModeWPS,
+  kCWSecurityModeDynamicWEP
+} CWSecurityMode;
+
+@interface CWNetwork (SnowLeopardSDK)
+@property(readonly) NSNumber* rssi;
+@property(readonly) NSNumber* securityMode;
+@end
+#endif
+
+// ----------------------------------------------------------------------------
+// The symbol for kCWSSIDDidChangeNotification is available in the
+// CoreWLAN.framework for OSX versions 10.6 through 10.10. The symbol is not
+// declared in the OSX 10.9+ SDK, so when compiling against an OSX 10.9+ SDK,
+// declare the symbol.
+// ----------------------------------------------------------------------------
+#if defined(MAC_OS_X_VERSION_10_9) && \
+    MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9
+BASE_EXPORT extern "C" NSString* const kCWSSIDDidChangeNotification;
+#endif
 #endif  // BASE_MAC_SDK_FORWARD_DECLARATIONS_H_