Move base/thread.h to base/threading, fix up callers to use the new location....

base/thread_restrictions.h

-// Copyright (c) 2010 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_THREAD_RESTRICTIONS_H_
-#define BASE_THREAD_RESTRICTIONS_H_
-
-#include "base/basictypes.h"
-
-namespace base {
-
-// Certain behavior is disallowed on certain threads.  ThreadRestrictions helps
-// enforce these rules.  Examples of such rules:
-//
-// * Do not do blocking IO (makes the thread janky)
-// * Do not access Singleton/LazyInstance (may lead to shutdown crashes)
-//
-// Here's more about how the protection works:
-//
-// 1) If a thread should not be allowed to make IO calls, mark it:
-//      base::ThreadRestrictions::SetIOAllowed(false);
-//    By default, threads *are* allowed to make IO calls.
-//    In Chrome browser code, IO calls should be proxied to the File thread.
-//
-// 2) If a function makes a call that will go out to disk, check whether the
-//    current thread is allowed:
-//      base::ThreadRestrictions::AssertIOAllowed();
-//
-// ThreadRestrictions does nothing in release builds; it is debug-only.
-//
-// Style tip: where should you put AssertIOAllowed checks?  It's best
-// if you put them as close to the disk access as possible, at the
-// lowest level.  This rule is simple to follow and helps catch all
-// callers.  For example, if your function GoDoSomeBlockingDiskCall()
-// only calls other functions in Chrome and not fopen(), you should go
-// add the AssertIOAllowed checks in the helper functions.
-
-class ThreadRestrictions {
- public:
-  // Constructing a ScopedAllowIO temporarily allows IO for the current
-  // thread.  Doing this is almost certainly always incorrect.
-  class ScopedAllowIO {
-   public:
-    ScopedAllowIO() { previous_value_ = SetIOAllowed(true); }
-    ~ScopedAllowIO() { SetIOAllowed(previous_value_); }
-   private:
-    // Whether IO is allowed when the ScopedAllowIO was constructed.
-    bool previous_value_;
-
-    DISALLOW_COPY_AND_ASSIGN(ScopedAllowIO);
-  };
-
-  // Constructing a ScopedAllowSingleton temporarily allows accessing for the
-  // current thread.  Doing this is almost always incorrect.
-  class ScopedAllowSingleton {
-   public:
-    ScopedAllowSingleton() { previous_value_ = SetSingletonAllowed(true); }
-    ~ScopedAllowSingleton() { SetSingletonAllowed(previous_value_); }
-   private:
-    // Whether singleton use is allowed when the ScopedAllowSingleton was
-    // constructed.
-    bool previous_value_;
-
-    DISALLOW_COPY_AND_ASSIGN(ScopedAllowSingleton);
-  };
-
-#ifndef NDEBUG
-  // Set whether the current thread to make IO calls.
-  // Threads start out in the *allowed* state.
-  // Returns the previous value.
-  static bool SetIOAllowed(bool allowed);
-
-  // Check whether the current thread is allowed to make IO calls,
-  // and DCHECK if not.  See the block comment above the class for
-  // a discussion of where to add these checks.
-  static void AssertIOAllowed();
-
-  // Set whether the current thread can use singletons.  Returns the previous
-  // value.
-  static bool SetSingletonAllowed(bool allowed);
-
-  // Check whether the current thread is allowed to use singletons (Singleton /
-  // LazyInstance).  DCHECKs if not.
-  static void AssertSingletonAllowed();
-#else
-  // In Release builds, inline the empty definitions of these functions so
-  // that they can be compiled out.
-  static bool SetIOAllowed(bool allowed) { return true; }
-  static void AssertIOAllowed() {}
-  static bool SetSingletonAllowed(bool allowed) { return true; }
-  static void AssertSingletonAllowed() {}
-#endif
-
- private:
-  DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions);
-};
-
-}  // namespace base
-
-#endif  // BASE_THREAD_RESTRICTIONS_H_