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diff --git a/security/sandbox/chromium/base/threading/thread_restrictions.h b/security/sandbox/chromium/base/threading/thread_restrictions.h
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+++ b/security/sandbox/chromium/base/threading/thread_restrictions.h
@@ -0,0 +1,680 @@
+// 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.
+
+#ifndef BASE_THREADING_THREAD_RESTRICTIONS_H_
+#define BASE_THREADING_THREAD_RESTRICTIONS_H_
+
+#include "base/base_export.h"
+#include "base/gtest_prod_util.h"
+#include "base/logging.h"
+#include "base/macros.h"
+
+// -----------------------------------------------------------------------------
+// Usage documentation
+// -----------------------------------------------------------------------------
+//
+// Overview:
+// This file exposes functions to ban and allow certain slow operations
+// on a per-thread basis. To annotate *usage* of such slow operations, refer to
+// scoped_blocking_call.h instead.
+//
+// Specific allowances that can be controlled in this file are:
+// - Blocking call: Refers to any call that causes the calling thread to wait
+//   off-CPU. It includes but is not limited to calls that wait on synchronous
+//   file I/O operations: read or write a file from disk, interact with a pipe
+//   or a socket, rename or delete a file, enumerate files in a directory, etc.
+//   Acquiring a low contention lock is not considered a blocking call.
+//
+// - Waiting on a //base sync primitive: Refers to calling one of these methods:
+//   - base::WaitableEvent::*Wait*
+//   - base::ConditionVariable::*Wait*
+//   - base::Process::WaitForExit*
+//
+// - Long CPU work: Refers to any code that takes more than 100 ms to
+//   run when there is no CPU contention and no hard page faults and therefore,
+//   is not suitable to run on a thread required to keep the browser responsive
+//   (where jank could be visible to the user).
+//
+// The following disallowance functions are offered:
+//  - DisallowBlocking(): Disallows blocking calls on the current thread.
+//  - DisallowBaseSyncPrimitives(): Disallows waiting on a //base sync primitive
+//    on the current thread.
+//  - DisallowUnresponsiveTasks() Disallows blocking calls, waiting on a //base
+//    sync primitive, and long cpu work on the current thread.
+//
+// In addition, scoped-allowance mechanisms are offered to make an exception
+// within a scope for a behavior that is normally disallowed.
+//  - ScopedAllowBlocking(ForTesting): Allows blocking calls.
+//  - ScopedAllowBaseSyncPrimitives(ForTesting)(OutsideBlockingScope): Allow
+//    waiting on a //base sync primitive. The OutsideBlockingScope suffix allows
+//    uses in a scope where blocking is also disallowed.
+//
+// Avoid using allowances outside of unit tests. In unit tests, use allowances
+// with the suffix "ForTesting".
+//
+// Prefer making blocking calls from tasks posted to base::ThreadPoolInstance
+// with base::MayBlock().
+//
+// Instead of waiting on a WaitableEvent or a ConditionVariable, prefer putting
+// the work that should happen after the wait in a continuation callback and
+// post it from where the WaitableEvent or ConditionVariable would have been
+// signaled. If something needs to be scheduled after many tasks have executed,
+// use base::BarrierClosure.
+//
+// On Windows, join processes asynchronously using base::win::ObjectWatcher.
+//
+// Where unavoidable, put ScopedAllow* instances in the narrowest scope possible
+// in the caller making the blocking call but no further down. For example: if a
+// Cleanup() method needs to do a blocking call, document Cleanup() as blocking
+// and add a ScopedAllowBlocking instance in callers that can't avoid making
+// this call from a context where blocking is banned, as such:
+//
+//   void Client::MyMethod() {
+//     (...)
+//     {
+//       // Blocking is okay here because XYZ.
+//       ScopedAllowBlocking allow_blocking;
+//       my_foo_->Cleanup();
+//     }
+//     (...)
+//   }
+//
+//   // This method can block.
+//   void Foo::Cleanup() {
+//     // Do NOT add the ScopedAllowBlocking in Cleanup() directly as that hides
+//     // its blocking nature from unknowing callers and defeats the purpose of
+//     // these checks.
+//     FlushStateToDisk();
+//   }
+//
+// Note: In rare situations where the blocking call is an implementation detail
+// (i.e. the impl makes a call that invokes AssertBlockingAllowed() but it
+// somehow knows that in practice this will not block), it might be okay to hide
+// the ScopedAllowBlocking instance in the impl with a comment explaining why
+// that's okay.
+
+class BrowserProcessImpl;
+class HistogramSynchronizer;
+class KeyStorageLinux;
+class NativeBackendKWallet;
+class NativeDesktopMediaList;
+class StartupTimeBomb;
+
+namespace android_webview {
+class AwFormDatabaseService;
+class CookieManager;
+class ScopedAllowInitGLBindings;
+class VizCompositorThreadRunnerWebView;
+}
+namespace audio {
+class OutputDevice;
+}
+namespace blink {
+class RTCVideoDecoderAdapter;
+class RTCVideoEncoder;
+class SourceStream;
+class VideoFrameResourceProvider;
+class WorkerThread;
+namespace scheduler {
+class WorkerThread;
+}
+}
+namespace cc {
+class CompletionEvent;
+class TileTaskManagerImpl;
+}
+namespace chromeos {
+class BlockingMethodCaller;
+namespace system {
+class StatisticsProviderImpl;
+}
+}
+namespace chrome_browser_net {
+class Predictor;
+}
+namespace chrome_cleaner {
+class SystemReportComponent;
+}
+namespace content {
+class BrowserGpuChannelHostFactory;
+class BrowserMainLoop;
+class BrowserProcessSubThread;
+class BrowserShutdownProfileDumper;
+class BrowserTestBase;
+class CategorizedWorkerPool;
+class DesktopCaptureDevice;
+class InProcessUtilityThread;
+class NestedMessagePumpAndroid;
+class RenderProcessHostImpl;
+class RenderWidgetHostViewMac;
+class RTCVideoDecoder;
+class SandboxHostLinux;
+class ScopedAllowWaitForDebugURL;
+class ServiceWorkerContextClient;
+class SoftwareOutputDeviceMus;
+class SynchronousCompositor;
+class SynchronousCompositorHost;
+class SynchronousCompositorSyncCallBridge;
+class TextInputClientMac;
+class WebContentsViewMac;
+}  // namespace content
+namespace cronet {
+class CronetPrefsManager;
+class CronetURLRequestContext;
+}  // namespace cronet
+namespace dbus {
+class Bus;
+}
+namespace disk_cache {
+class BackendImpl;
+class InFlightIO;
+}
+namespace functions {
+class ExecScriptScopedAllowBaseSyncPrimitives;
+}
+namespace history_report {
+class HistoryReportJniBridge;
+}
+namespace gpu {
+class GpuChannelHost;
+}
+namespace leveldb_env {
+class DBTracker;
+}
+namespace media {
+class AudioInputDevice;
+class AudioOutputDevice;
+class BlockingUrlProtocol;
+class PaintCanvasVideoRenderer;
+}
+namespace memory_instrumentation {
+class OSMetrics;
+}
+namespace midi {
+class TaskService;  // https://crbug.com/796830
+}
+namespace module_installer {
+class ScopedAllowModulePakLoad;
+}
+namespace mojo {
+class CoreLibraryInitializer;
+class SyncCallRestrictions;
+namespace core {
+class ScopedIPCSupport;
+}
+}
+namespace printing {
+class PrintJobWorker;
+class PrinterQuery;
+}
+namespace rlz_lib {
+class FinancialPing;
+}
+namespace syncer {
+class GetLocalChangesRequest;
+class HttpBridge;
+class ModelSafeWorker;
+}
+namespace ui {
+class CommandBufferClientImpl;
+class CommandBufferLocal;
+class GpuState;
+class MaterialDesignController;
+}
+namespace weblayer {
+class WebLayerPathProvider;
+}
+namespace net {
+class MultiThreadedCertVerifierScopedAllowBaseSyncPrimitives;
+class MultiThreadedProxyResolverScopedAllowJoinOnIO;
+class NetworkChangeNotifierMac;
+class NetworkConfigWatcherMacThread;
+namespace internal {
+class AddressTrackerLinux;
+}
+}
+
+namespace proxy_resolver {
+class ScopedAllowThreadJoinForProxyResolverV8Tracing;
+}
+
+namespace remoting {
+class AutoThread;
+namespace protocol {
+class ScopedAllowThreadJoinForWebRtcTransport;
+}
+}
+
+namespace resource_coordinator {
+class TabManagerDelegate;
+}
+
+namespace service_manager {
+class ServiceProcessLauncher;
+}
+
+namespace shell_integration_linux {
+class LaunchXdgUtilityScopedAllowBaseSyncPrimitives;
+}
+
+namespace ui {
+class WindowResizeHelperMac;
+}
+
+namespace viz {
+class HostGpuMemoryBufferManager;
+}
+
+namespace vr {
+class VrShell;
+}
+
+namespace web {
+class WebMainLoop;
+class WebSubThread;
+}
+
+namespace weblayer {
+class ProfileImpl;
+}
+
+namespace webrtc {
+class DesktopConfigurationMonitor;
+}
+
+namespace base {
+
+namespace sequence_manager {
+namespace internal {
+class TaskQueueImpl;
+}
+}  // namespace sequence_manager
+
+namespace android {
+class JavaHandlerThread;
+}
+
+namespace internal {
+class JobTaskSource;
+class TaskTracker;
+}
+
+class AdjustOOMScoreHelper;
+class FileDescriptorWatcher;
+class GetAppOutputScopedAllowBaseSyncPrimitives;
+class ScopedAllowThreadRecallForStackSamplingProfiler;
+class SimpleThread;
+class StackSamplingProfiler;
+class Thread;
+
+#if DCHECK_IS_ON()
+#define INLINE_IF_DCHECK_IS_OFF BASE_EXPORT
+#define EMPTY_BODY_IF_DCHECK_IS_OFF
+#else
+#define INLINE_IF_DCHECK_IS_OFF inline
+
+// The static_assert() eats follow-on semicolons. `= default` would work
+// too, but it makes clang realize that all the Scoped classes are no-ops in
+// non-dcheck builds and it starts emitting many -Wunused-variable warnings.
+#define EMPTY_BODY_IF_DCHECK_IS_OFF \
+  {}                                \
+  static_assert(true, "")
+#endif
+
+namespace internal {
+
+// Asserts that blocking calls are allowed in the current scope. This is an
+// internal call, external code should use ScopedBlockingCall instead, which
+// serves as a precise annotation of the scope that may/will block.
+INLINE_IF_DCHECK_IS_OFF void AssertBlockingAllowed()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+}  // namespace internal
+
+// Disallows blocking on the current thread.
+INLINE_IF_DCHECK_IS_OFF void DisallowBlocking() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+// Disallows blocking calls within its scope.
+class BASE_EXPORT ScopedDisallowBlocking {
+ public:
+  ScopedDisallowBlocking() EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedDisallowBlocking() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+ private:
+#if DCHECK_IS_ON()
+  const bool was_disallowed_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedDisallowBlocking);
+};
+
+class BASE_EXPORT ScopedAllowBlocking {
+ private:
+  FRIEND_TEST_ALL_PREFIXES(ThreadRestrictionsTest, ScopedAllowBlocking);
+  friend class ScopedAllowBlockingForTesting;
+
+  // This can only be instantiated by friends. Use ScopedAllowBlockingForTesting
+  // in unit tests to avoid the friend requirement.
+  friend class AdjustOOMScoreHelper;
+  friend class android_webview::ScopedAllowInitGLBindings;
+  friend class content::BrowserProcessSubThread;
+  friend class content::RenderWidgetHostViewMac;  // http://crbug.com/121917
+  friend class content::WebContentsViewMac;
+  friend class cronet::CronetPrefsManager;
+  friend class cronet::CronetURLRequestContext;
+  friend class memory_instrumentation::OSMetrics;
+  friend class module_installer::ScopedAllowModulePakLoad;
+  friend class mojo::CoreLibraryInitializer;
+  friend class printing::PrintJobWorker;
+  friend class resource_coordinator::TabManagerDelegate;  // crbug.com/778703
+  friend class ui::MaterialDesignController;
+  friend class web::WebSubThread;
+  friend class StackSamplingProfiler;
+  friend class weblayer::ProfileImpl;
+  friend class content::RenderProcessHostImpl;
+  friend class weblayer::WebLayerPathProvider;
+
+  ScopedAllowBlocking() EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedAllowBlocking() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+#if DCHECK_IS_ON()
+  const bool was_disallowed_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowBlocking);
+};
+
+class ScopedAllowBlockingForTesting {
+ public:
+  ScopedAllowBlockingForTesting() {}
+  ~ScopedAllowBlockingForTesting() {}
+
+ private:
+#if DCHECK_IS_ON()
+  ScopedAllowBlocking scoped_allow_blocking_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowBlockingForTesting);
+};
+
+INLINE_IF_DCHECK_IS_OFF void DisallowBaseSyncPrimitives()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+class BASE_EXPORT ScopedAllowBaseSyncPrimitives {
+ private:
+  // This can only be instantiated by friends. Use
+  // ScopedAllowBaseSyncPrimitivesForTesting in unit tests to avoid the friend
+  // requirement.
+  FRIEND_TEST_ALL_PREFIXES(ThreadRestrictionsTest,
+                           ScopedAllowBaseSyncPrimitives);
+  FRIEND_TEST_ALL_PREFIXES(ThreadRestrictionsTest,
+                           ScopedAllowBaseSyncPrimitivesResetsState);
+  FRIEND_TEST_ALL_PREFIXES(ThreadRestrictionsTest,
+                           ScopedAllowBaseSyncPrimitivesWithBlockingDisallowed);
+
+  // Allowed usage:
+  friend class SimpleThread;
+  friend class base::GetAppOutputScopedAllowBaseSyncPrimitives;
+  friend class blink::SourceStream;
+  friend class blink::WorkerThread;
+  friend class blink::scheduler::WorkerThread;
+  friend class chrome_cleaner::SystemReportComponent;
+  friend class content::BrowserMainLoop;
+  friend class content::BrowserProcessSubThread;
+  friend class content::ServiceWorkerContextClient;
+  friend class functions::ExecScriptScopedAllowBaseSyncPrimitives;
+  friend class history_report::HistoryReportJniBridge;
+  friend class internal::TaskTracker;
+  friend class leveldb_env::DBTracker;
+  friend class media::BlockingUrlProtocol;
+  friend class mojo::core::ScopedIPCSupport;
+  friend class net::MultiThreadedCertVerifierScopedAllowBaseSyncPrimitives;
+  friend class rlz_lib::FinancialPing;
+  friend class shell_integration_linux::
+      LaunchXdgUtilityScopedAllowBaseSyncPrimitives;
+  friend class syncer::HttpBridge;
+  friend class syncer::GetLocalChangesRequest;
+  friend class syncer::ModelSafeWorker;
+  friend class webrtc::DesktopConfigurationMonitor;
+
+  // Usage that should be fixed:
+  friend class ::NativeBackendKWallet;            // http://crbug.com/125331
+  friend class ::chromeos::system::
+      StatisticsProviderImpl;                      // http://crbug.com/125385
+  friend class content::TextInputClientMac;        // http://crbug.com/121917
+  friend class blink::VideoFrameResourceProvider;  // http://crbug.com/878070
+
+  ScopedAllowBaseSyncPrimitives() EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedAllowBaseSyncPrimitives() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+#if DCHECK_IS_ON()
+  const bool was_disallowed_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowBaseSyncPrimitives);
+};
+
+class BASE_EXPORT ScopedAllowBaseSyncPrimitivesOutsideBlockingScope {
+ private:
+  // This can only be instantiated by friends. Use
+  // ScopedAllowBaseSyncPrimitivesForTesting in unit tests to avoid the friend
+  // requirement.
+  FRIEND_TEST_ALL_PREFIXES(ThreadRestrictionsTest,
+                           ScopedAllowBaseSyncPrimitivesOutsideBlockingScope);
+  FRIEND_TEST_ALL_PREFIXES(
+      ThreadRestrictionsTest,
+      ScopedAllowBaseSyncPrimitivesOutsideBlockingScopeResetsState);
+
+  // Allowed usage:
+  friend class ::BrowserProcessImpl;  // http://crbug.com/125207
+  friend class ::KeyStorageLinux;
+  friend class ::NativeDesktopMediaList;
+  friend class ::StartupTimeBomb;
+  friend class android::JavaHandlerThread;
+  friend class android_webview::
+      AwFormDatabaseService;  // http://crbug.com/904431
+  friend class android_webview::CookieManager;
+  friend class android_webview::VizCompositorThreadRunnerWebView;
+  friend class audio::OutputDevice;
+  friend class base::sequence_manager::internal::TaskQueueImpl;
+  friend class base::FileDescriptorWatcher;
+  friend class base::internal::JobTaskSource;
+  friend class base::ScopedAllowThreadRecallForStackSamplingProfiler;
+  friend class base::StackSamplingProfiler;
+  friend class blink::RTCVideoDecoderAdapter;
+  friend class blink::RTCVideoEncoder;
+  friend class cc::TileTaskManagerImpl;
+  friend class content::CategorizedWorkerPool;
+  friend class content::DesktopCaptureDevice;
+  friend class content::InProcessUtilityThread;
+  friend class content::RTCVideoDecoder;
+  friend class content::SandboxHostLinux;
+  friend class content::ScopedAllowWaitForDebugURL;
+  friend class content::SynchronousCompositor;
+  friend class content::SynchronousCompositorHost;
+  friend class content::SynchronousCompositorSyncCallBridge;
+  friend class media::AudioInputDevice;
+  friend class media::AudioOutputDevice;
+  friend class media::PaintCanvasVideoRenderer;
+  friend class mojo::SyncCallRestrictions;
+  friend class net::NetworkConfigWatcherMacThread;
+  friend class viz::HostGpuMemoryBufferManager;
+  friend class vr::VrShell;
+
+  // Usage that should be fixed:
+  friend class ::chromeos::BlockingMethodCaller;  // http://crbug.com/125360
+  friend class base::Thread;                      // http://crbug.com/918039
+  friend class cc::CompletionEvent;               // http://crbug.com/902653
+  friend class content::
+      BrowserGpuChannelHostFactory;                 // http://crbug.com/125248
+  friend class dbus::Bus;                           // http://crbug.com/125222
+  friend class disk_cache::BackendImpl;             // http://crbug.com/74623
+  friend class disk_cache::InFlightIO;              // http://crbug.com/74623
+  friend class gpu::GpuChannelHost;                 // http://crbug.com/125264
+  friend class remoting::protocol::
+      ScopedAllowThreadJoinForWebRtcTransport;      // http://crbug.com/660081
+  friend class midi::TaskService;                   // https://crbug.com/796830
+  friend class net::internal::AddressTrackerLinux;  // http://crbug.com/125097
+  friend class net::
+      MultiThreadedProxyResolverScopedAllowJoinOnIO;  // http://crbug.com/69710
+  friend class net::NetworkChangeNotifierMac;         // http://crbug.com/125097
+  friend class printing::PrinterQuery;                 // http://crbug.com/66082
+  friend class proxy_resolver::
+      ScopedAllowThreadJoinForProxyResolverV8Tracing;  // http://crbug.com/69710
+  friend class remoting::AutoThread;  // https://crbug.com/944316
+  // Not used in production yet, https://crbug.com/844078.
+  friend class service_manager::ServiceProcessLauncher;
+  friend class ui::WindowResizeHelperMac;  // http://crbug.com/902829
+
+  ScopedAllowBaseSyncPrimitivesOutsideBlockingScope()
+      EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedAllowBaseSyncPrimitivesOutsideBlockingScope()
+      EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+#if DCHECK_IS_ON()
+  const bool was_disallowed_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowBaseSyncPrimitivesOutsideBlockingScope);
+};
+
+class BASE_EXPORT ScopedAllowBaseSyncPrimitivesForTesting {
+ public:
+  ScopedAllowBaseSyncPrimitivesForTesting() EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedAllowBaseSyncPrimitivesForTesting() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+ private:
+#if DCHECK_IS_ON()
+  const bool was_disallowed_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowBaseSyncPrimitivesForTesting);
+};
+
+// Counterpart to base::DisallowUnresponsiveTasks() for tests to allow them to
+// block their thread after it was banned.
+class BASE_EXPORT ScopedAllowUnresponsiveTasksForTesting {
+ public:
+  ScopedAllowUnresponsiveTasksForTesting() EMPTY_BODY_IF_DCHECK_IS_OFF;
+  ~ScopedAllowUnresponsiveTasksForTesting() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+ private:
+#if DCHECK_IS_ON()
+  const bool was_disallowed_base_sync_;
+  const bool was_disallowed_blocking_;
+  const bool was_disallowed_cpu_;
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedAllowUnresponsiveTasksForTesting);
+};
+
+namespace internal {
+
+// Asserts that waiting on a //base sync primitive is allowed in the current
+// scope.
+INLINE_IF_DCHECK_IS_OFF void AssertBaseSyncPrimitivesAllowed()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+// Resets all thread restrictions on the current thread.
+INLINE_IF_DCHECK_IS_OFF void ResetThreadRestrictionsForTesting()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+}  // namespace internal
+
+// Asserts that running long CPU work is allowed in the current scope.
+INLINE_IF_DCHECK_IS_OFF void AssertLongCPUWorkAllowed()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+INLINE_IF_DCHECK_IS_OFF void DisallowUnresponsiveTasks()
+    EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+class BASE_EXPORT ThreadRestrictions {
+ public:
+  // Constructing a ScopedAllowIO temporarily allows IO for the current
+  // thread.  Doing this is almost certainly always incorrect.
+  //
+  // DEPRECATED. Use ScopedAllowBlocking(ForTesting).
+  class BASE_EXPORT ScopedAllowIO {
+   public:
+    ScopedAllowIO() EMPTY_BODY_IF_DCHECK_IS_OFF;
+    ~ScopedAllowIO() EMPTY_BODY_IF_DCHECK_IS_OFF;
+
+   private:
+#if DCHECK_IS_ON()
+    const bool was_allowed_;
+#endif
+
+    DISALLOW_COPY_AND_ASSIGN(ScopedAllowIO);
+  };
+
+#if DCHECK_IS_ON()
+  // Set whether the current thread to make IO calls.
+  // Threads start out in the *allowed* state.
+  // Returns the previous value.
+  //
+  // DEPRECATED. Use ScopedAllowBlocking(ForTesting) or ScopedDisallowBlocking.
+  static bool SetIOAllowed(bool allowed);
+
+  // 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();
+
+  // Disable waiting on the current thread. Threads start out in the *allowed*
+  // state. Returns the previous value.
+  //
+  // DEPRECATED. Use DisallowBaseSyncPrimitives.
+  static void DisallowWaiting();
+#else
+  // Inline the empty definitions of these functions so that they can be
+  // compiled out.
+  static bool SetIOAllowed(bool allowed) { return true; }
+  static bool SetSingletonAllowed(bool allowed) { return true; }
+  static void AssertSingletonAllowed() {}
+  static void DisallowWaiting() {}
+#endif
+
+ private:
+  // DO NOT ADD ANY OTHER FRIEND STATEMENTS.
+  // BEGIN ALLOWED USAGE.
+  friend class content::BrowserMainLoop;
+  friend class content::BrowserShutdownProfileDumper;
+  friend class content::BrowserTestBase;
+  friend class content::ScopedAllowWaitForDebugURL;
+  friend class ::HistogramSynchronizer;
+  friend class internal::TaskTracker;
+  friend class web::WebMainLoop;
+  friend class MessagePumpDefault;
+  friend class PlatformThread;
+  friend class ui::CommandBufferClientImpl;
+  friend class ui::CommandBufferLocal;
+  friend class ui::GpuState;
+
+  // END ALLOWED USAGE.
+  // BEGIN USAGE THAT NEEDS TO BE FIXED.
+  friend class chrome_browser_net::Predictor;     // http://crbug.com/78451
+#if !defined(OFFICIAL_BUILD)
+  friend class content::SoftwareOutputDeviceMus;  // Interim non-production code
+#endif
+// END USAGE THAT NEEDS TO BE FIXED.
+
+#if DCHECK_IS_ON()
+  // DEPRECATED. Use ScopedAllowBaseSyncPrimitives.
+  static bool SetWaitAllowed(bool allowed);
+#else
+  static bool SetWaitAllowed(bool allowed) { return true; }
+#endif
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(ThreadRestrictions);
+};
+
+#undef INLINE_IF_DCHECK_IS_OFF
+#undef EMPTY_BODY_IF_DCHECK_IS_OFF
+
+}  // namespace base
+
+#endif  // BASE_THREADING_THREAD_RESTRICTIONS_H_