Mojo: Modify plumbing for the WaitMany implementation.

mojo/system/core.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 MOJO_SYSTEM_CORE_H_
 #define MOJO_SYSTEM_CORE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/ref_counted.h"
@@ skipping 90 matching lines @@
                        uint64_t offset,
                        uint64_t num_bytes,
                        UserPointer<void*> buffer,
                        MojoMapBufferFlags flags);
   MojoResult UnmapBuffer(UserPointerValue<void> buffer);
 
  private:
   friend bool internal::ShutdownCheckNoLeaks(Core*);
 
   // Internal implementation of |Wait()| and |WaitMany()|; doesn't do basic
-  // validation of arguments.
+  // validation of arguments. |*result_index| is only set if the result (whether
+  // success or failure) applies to a specific handle, so its value should be
+  // preinitialized to |static_cast<uint32_t>(-1)|.
   MojoResult WaitManyInternal(const MojoHandle* handles,
                               const MojoHandleSignals* signals,
                               uint32_t num_handles,
-                              MojoDeadline deadline);
+                              MojoDeadline deadline,
+                              uint32_t* result_index);
 
   // ---------------------------------------------------------------------------
 
   // TODO(vtl): |handle_table_lock_| should be a reader-writer lock (if only we
   // had them).
   base::Lock handle_table_lock_;  // Protects |handle_table_|.
   HandleTable handle_table_;
 
   base::Lock mapping_table_lock_;  // Protects |mapping_table_|.
   MappingTable mapping_table_;
 
   // ---------------------------------------------------------------------------
 
   DISALLOW_COPY_AND_ASSIGN(Core);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_CORE_H_