Chromium roll (https://codereview.chromium.org/976353002)

base/memory/discardable_shared_memory.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef BASE_MEMORY_DISCARDABLE_SHARED_MEMORY_H_
 #define BASE_MEMORY_DISCARDABLE_SHARED_MEMORY_H_
 
 #include "base/base_export.h"
 #include "base/logging.h"
 #include "base/memory/shared_memory.h"
@@ skipping 56 matching lines @@
   // previously locked range is undefined.
   // |offset| and |length| must both be a multiple of the page size as returned
   // by GetPageSize().
   // Passing 0 for |length| means "everything onward".
   void Unlock(size_t offset, size_t length);
 
   // Gets a pointer to the opened discardable memory space. Discardable memory
   // must have been mapped via Map().
   void* memory() const;
 
-  // Returns the last know usage time for DiscardableSharedMemory object. This
+  // Returns the last known usage time for DiscardableSharedMemory object. This
   // may be earlier than the "true" usage time when memory has been used by a
   // different process. Returns NULL time if purged.
   Time last_known_usage() const { return last_known_usage_; }
 
   // This returns true and sets |last_known_usage_| to 0 if
   // DiscardableSharedMemory object was successfully purged. Purging can fail
   // for two reasons; object might be locked or our last known usage timestamp
   // might be out of date. Last known usage time is updated to |current_time|
   // if locked or the actual last usage timestamp if unlocked. It is often
-  // neccesary to call this function twice for the object to successfully be
+  // necessary to call this function twice for the object to successfully be
   // purged. First call, updates |last_known_usage_|. Second call, successfully
   // purges the object using the updated |last_known_usage_|.
   // Note: there is no guarantee that multiple calls to this function will
   // successfully purge object. DiscardableSharedMemory object might be locked
   // or another thread/process might be able to lock and unlock it in between
   // each call.
   bool Purge(Time current_time);
 
   // Purge and release as much memory as possible to the OS.
   // Note: The amount of memory that can be released to the OS is platform
@@ skipping 32 matching lines @@
   // synchronized somehow. Use a collision warner to detect incorrect usage.
   DFAKE_MUTEX(thread_collision_warner_);
   Time last_known_usage_;
 
   DISALLOW_COPY_AND_ASSIGN(DiscardableSharedMemory);
 };
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_DISCARDABLE_SHARED_MEMORY_H_