Fix some grammatical errors in native_client_sdk/

native_client_sdk/src/build_tools/debug_server/port/thread.h

 /*
  * Copyright (c) 2012 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.
  */
 
 
 // This module defines the interface for interacting with platform specific
 // threads  .  This API provides a mechanism to query for a thread, by using
 // the acquire method with the ID of a pre-existing thread.   The register
@@ skipping 13 matching lines @@
 
 namespace port {
 
 class IThread {
  public:
   enum State {
     DEAD     =-1,  // The thread has exited or been killed
     RUNNING  = 0,  // The thread is currently running
     SUSPENDED= 1,  // The thread has been suspended
     SIGNALED = 2,  // The thread is signaled
-    SYSCALL  = 3   // In a sys call, it's registers can not be modified.
+    SYSCALL  = 3   // In a sys call, its registers can not be modified.
   };
 
   typedef void (*CatchFunc_t)(uint32_t id, int8_t sig, void *cookie);
   typedef std::map<uint32_t, IThread*> ThreadMap_t;
 
   virtual uint32_t GetId() = 0;
   virtual State GetState() = 0;
 
   virtual bool SetStep(bool on) = 0;
 
@@ skipping 10 matching lines @@
   static void SetExceptionCatch(CatchFunc_t func, void *cookie);
 
  protected:
   virtual ~IThread() {}  // Prevent delete of base pointer
 };
 
 }  // namespace port
 
 #endif  // PORT_THREAD_H_