Revert "base: Implement browser process support for discardable memory."

content/common/host_discardable_shared_memory_manager.h

Index: content/common/host_discardable_shared_memory_manager.h
diff --git a/content/common/host_discardable_shared_memory_manager.h b/content/common/host_discardable_shared_memory_manager.h
index 6998f0d0c0351a120e97e25d1b68ef4e7e51adf2..624dd2fdf164895db32e4427645d28a7b9e3f209 100644
--- a/content/common/host_discardable_shared_memory_manager.h
+++ b/content/common/host_discardable_shared_memory_manager.h
@@ -71,10 +71,6 @@ class CONTENT_EXPORT HostDiscardableSharedMemoryManager
     return a.memory->last_known_usage() > b.memory->last_known_usage();
   }
 
-  void AllocateLockedDiscardableSharedMemory(
-      base::ProcessHandle process_handle,
-      size_t size,
-      base::SharedMemoryHandle* shared_memory_handle);
   void OnMemoryPressure(
       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
   void ReduceMemoryUsageUntilWithinMemoryLimit();