Make command buffer commands and immediate data volatile

gpu/command_buffer/common/mailbox.h

 // Copyright 2013 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 GPU_COMMAND_BUFFER_MAILBOX_H_
 #define GPU_COMMAND_BUFFER_MAILBOX_H_
 
 #include <stdint.h>
 #include <string.h>
 
@@ skipping 10 matching lines @@
 // This name can be passed across processes permitting one context to share
 // texture image data with another. The mailbox name consists of a random
 // set of bytes, optionally with a checksum (in debug mode) to verify the
 // name is valid.
 // See src/gpu/GLES2/extensions/CHROMIUM/CHROMIUM_texture_mailbox.txt for more
 // details.
 struct GPU_EXPORT Mailbox {
   using Name = int8_t[GL_MAILBOX_SIZE_CHROMIUM];
 
   Mailbox();
+
+  static Mailbox FromVolatile(const volatile Mailbox& other) {
+    // Because the copy constructor is trivial, const_cast is safe.
+    return const_cast<const Mailbox&>(other);
+  }
+
   bool IsZero() const;
   void SetZero();
   void SetName(const int8_t* name);
 
   // Generate a unique unguessable mailbox name.
   static Mailbox Generate();
 
   // Verify that the mailbox was created through Mailbox::Generate. This only
   // works in Debug (always returns true in Release). This is not a secure
   // check, only to catch bugs where clients forgot to call Mailbox::Generate.
   bool Verify() const;
 
   Name name;
 
   bool operator<(const Mailbox& other) const {
     return memcmp(this, &other, sizeof other) < 0;
   }
   bool operator==(const Mailbox& other) const {
     return memcmp(this, &other, sizeof other) == 0;
   }
   bool operator!=(const Mailbox& other) const {
     return !operator==(other);
   }
 };
 
 }  // namespace gpu
 
 #endif  // GPU_COMMAND_BUFFER_MAILBOX_H_