Update from chromium https://crrev.com/301315

sandbox/linux/bpf_dsl/bpf_dsl.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 SANDBOX_LINUX_BPF_DSL_BPF_DSL_H_
 #define SANDBOX_LINUX_BPF_DSL_BPF_DSL_H_
 
 #include <stdint.h>
 
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
+#include "sandbox/linux/bpf_dsl/bpf_dsl_forward.h"
 #include "sandbox/linux/bpf_dsl/cons.h"
 #include "sandbox/linux/bpf_dsl/trap_registry.h"
 #include "sandbox/sandbox_export.h"
 
 // The sandbox::bpf_dsl namespace provides a domain-specific language
 // to make writing BPF policies more expressive.  In general, the
 // object types all have value semantics (i.e., they can be copied
 // around, returned from or passed to function calls, etc. without any
 // surprising side effects), though not all support assignment.
 //
 // An idiomatic and demonstrative (albeit silly) example of this API
 // would be:
 //
 //      #include "sandbox/linux/bpf_dsl/bpf_dsl.h"
 //
 //      using namespace sandbox::bpf_dsl;
 //
-//      class SillyPolicy : public SandboxBPFDSLPolicy {
+//      class SillyPolicy : public Policy {
 //       public:
 //        SillyPolicy() {}
 //        virtual ~SillyPolicy() {}
 //        virtual ResultExpr EvaluateSyscall(int sysno) const override {
 //          if (sysno == __NR_fcntl) {
 //            Arg<int> fd(0), cmd(1);
 //            Arg<unsigned long> flags(2);
 //            const uint64_t kGoodFlags = O_ACCMODE | O_NONBLOCK;
 //            return If(fd == 0 && cmd == F_SETFL && (flags & ~kGoodFlags) == 0,
 //                      Allow())
@@ skipping 22 matching lines @@
 // The semantics of each function and operator are intended to be
 // intuitive, but are described in more detail below.
 //
 // (Credit to Sean Parent's "Inheritance is the Base Class of Evil"
 // talk at Going Native 2013 for promoting value semantics via shared
 // pointers to immutable state.)
 
 namespace sandbox {
 namespace bpf_dsl {
 
-// Forward declarations of classes; see below for proper documentation.
-class Elser;
-template <typename T>
-class Caser;
-namespace internal {
-class ResultExprImpl;
-class BoolExprImpl;
-}
-
-}  // namespace bpf_dsl
-}  // namespace sandbox
-
-extern template class SANDBOX_EXPORT
-    scoped_refptr<const sandbox::bpf_dsl::internal::BoolExprImpl>;
-extern template class SANDBOX_EXPORT
-    scoped_refptr<const sandbox::bpf_dsl::internal::ResultExprImpl>;
-
-namespace sandbox {
-namespace bpf_dsl {
-
 // ResultExpr is an opaque reference to an immutable result expression tree.
 typedef scoped_refptr<const internal::ResultExprImpl> ResultExpr;
 
 // BoolExpr is an opaque reference to an immutable boolean expression tree.
 typedef scoped_refptr<const internal::BoolExprImpl> BoolExpr;
 
-// Interface to implement to define a BPF sandbox policy.
-// TODO(mdempsky): "sandbox::bpf_dsl::SandboxBPFDSLPolicy" is
-// tediously repetitive; rename to just "Policy".
-class SANDBOX_EXPORT SandboxBPFDSLPolicy {
- public:
-  SandboxBPFDSLPolicy() {}
-  virtual ~SandboxBPFDSLPolicy() {}
-
-  // User extension point for writing custom sandbox policies.
-  // The returned ResultExpr will control how the kernel responds to the
-  // specified system call number.
-  virtual ResultExpr EvaluateSyscall(int sysno) const = 0;
-
-  // Optional overload for specifying alternate behavior for invalid
-  // system calls.  The default is to return ENOSYS.
-  virtual ResultExpr InvalidSyscall() const;
-
-  // Helper method so policies can just write Trap(func, aux).
-  static ResultExpr Trap(TrapRegistry::TrapFnc trap_func, const void* aux);
-
- private:
-  DISALLOW_COPY_AND_ASSIGN(SandboxBPFDSLPolicy);
-};
-
 // Allow specifies a result that the system call should be allowed to
 // execute normally.
 SANDBOX_EXPORT ResultExpr Allow();
 
 // Error specifies a result that the system call should fail with
 // error number |err|.  As a special case, Error(0) will result in the
 // system call appearing to have succeeded, but without having any
 // side effects.
 SANDBOX_EXPORT ResultExpr Error(int err);
 
@@ skipping 216 matching lines @@
 
 template <typename T>
 ResultExpr Caser<T>::Default(ResultExpr result) const {
   return elser_.Else(result);
 }
 
 }  // namespace bpf_dsl
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_BPF_DSL_BPF_DSL_H_