[Infra] Only compile core extension headers once

Author: ncooke3

FirebaseCore/Extension/FIRAppInternal.h

@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#ifndef FIREBASECORE_FIRAPPINTERNAL_H
+#define FIREBASECORE_FIRAPPINTERNAL_H
+
 #import <FirebaseCore/FIRApp.h>
 
 @class FIRComponentContainer;
@@ -175,3 +178,5 @@ extern NSString *const FIRAuthStateDidChangeInternalNotificationUIDKey;
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRAPPINTERNAL_H

FirebaseCore/Extension/FIRComponent.h

@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#ifndef FIREBASECORE_FIRCOMPONENT_H
+#define FIREBASECORE_FIRCOMPONENT_H
+
 #import <Foundation/Foundation.h>
 
 @class FIRApp;
@@ -82,3 +85,5 @@ NS_SWIFT_NAME(init(_:instantiationTiming:creationBlock:));
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRCOMPONENT_H

FirebaseCore/Extension/FIRComponentContainer.h

@@ -13,6 +13,10 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
+#ifndef FIREBASECORE_FIRCOMPONENTCONTAINER_H
+#define FIREBASECORE_FIRCOMPONENTCONTAINER_H
+
 #import <Foundation/Foundation.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -43,3 +47,5 @@ NS_SWIFT_NAME(FirebaseComponentContainer)
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRCOMPONENTCONTAINER_H

FirebaseCore/Extension/FIRComponentType.h

@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#ifndef FIREBASECORE_FIRCOMPONENTTYPE_H
+#define FIREBASECORE_FIRCOMPONENTTYPE_H
+
 #import <Foundation/Foundation.h>
 
 @class FIRComponentContainer;
@@ -33,3 +36,5 @@ NS_SWIFT_NAME(ComponentType)
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRCOMPONENTTYPE_H

FirebaseCore/Extension/FIRHeartbeatLogger.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef FIREBASECORE_FIRHEARTBEATLOGGER_H
+#define FIREBASECORE_FIRHEARTBEATLOGGER_H
+
 #import <Foundation/Foundation.h>
 
 NS_ASSUME_NONNULL_BEGIN
@@ -102,3 +105,5 @@ NSString *_Nullable FIRHeaderValueFromHeartbeatsPayload(FIRHeartbeatsPayload *he
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRHEARTBEATLOGGER_H

FirebaseCore/Extension/FIRLibrary.h

@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#ifndef FIREBASECORE_FIRLIBRARY_H
+#define FIREBASECORE_FIRLIBRARY_H
+
 #ifndef FIRLibrary_h
 #define FIRLibrary_h
 
@@ -37,3 +40,5 @@ NS_SWIFT_NAME(Library)
 NS_ASSUME_NONNULL_END
 
 #endif /* FIRLibrary_h */
+
+#endif  // FIREBASECORE_FIRLIBRARY_H

FirebaseCore/Extension/FIRLogger.h

@@ -14,6 +14,9 @@
  * limitations under the License.
  */
 
+#ifndef FIREBASECORE_FIRLOGGER_H
+#define FIREBASECORE_FIRLOGGER_H
+
 #import <Foundation/Foundation.h>
 
 typedef NS_ENUM(NSInteger, FIRLoggerLevel);
@@ -191,3 +194,5 @@ NS_SWIFT_NAME(FirebaseLogger)
 @end
 
 NS_ASSUME_NONNULL_END
+
+#endif  // FIREBASECORE_FIRLOGGER_H

FirebaseCore/Extension/FirebaseCoreInternal.h

@@ -12,6 +12,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+#ifndef FIREBASECORE_FIREBASECOREINTERNAL_H
+#define FIREBASECORE_FIREBASECOREINTERNAL_H
+
 @import FirebaseCore;
 
 #import "FIRAppInternal.h"
@@ -21,3 +24,5 @@
 #import "FIRHeartbeatLogger.h"
 #import "FIRLibrary.h"
 #import "FIRLogger.h"
+
+#endif  // FIREBASECORE_FIREBASECOREINTERNAL_H