Further clean up pepper's use of SharedMemory.

content/ppapi_plugin/ppapi_thread.cc

 // 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.
 
 #include "content/ppapi_plugin/ppapi_thread.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/cpu.h"
@@ skipping 184 matching lines @@
   }
 #endif
 
   DCHECK(peer_pid != base::kNullProcessId);
   return BrokerGetFileHandleForProcess(handle, peer_pid, should_close_source);
 }
 
 base::SharedMemoryHandle PpapiThread::ShareSharedMemoryHandleWithRemote(
     const base::SharedMemoryHandle& handle,
     base::ProcessId remote_pid) {
-  base::PlatformFile local_platform_file =
-#if defined(OS_POSIX)
-      handle.fd;
-#elif defined(OS_WIN)
-      handle;
+#if defined(OS_WIN)
+  if (peer_handle_.IsValid()) {
+    DCHECK(is_broker_);
+    return IPC::GetFileHandleForProcess(handle, peer_handle_.Get(), false);
+  }
+#endif
+
+  DCHECK(remote_pid != base::kNullProcessId);
+#if defined(OS_WIN) || defined(OS_MACOSX)
+  base::SharedMemoryHandle duped_handle;

[piman, 2015/06/03 17:44:44]

nit: just initialize this with base::SharedMemory::NULLHandle() and return it
unconditionally?

[erikchen, 2015/06/03 17:58:31]

Your suggestion saves 3 lines of code, but it makes the assumption that if
BrokerDuplicateSharedMemoryHandle fails, it will not touch duped_handle. (Having
looked through the current implementation, I think this is true, although it
depends on implementation of Windows's DuplicateHandle() function, and I'm
generally not inclined to trust anything developed by Microsoft.)

I think that the current code more clearly reflects the semantics of
BrokerDuplicateSharedMemoryHandle(). Are you okay with the current
implementation?

+  bool success =
+      BrokerDuplicateSharedMemoryHandle(handle, remote_pid, &duped_handle);
+  if (success)
+    return duped_handle;
+  return base::SharedMemory::NULLHandle();
 #else
-#error Not implemented.
-#endif
-  return PpapiThread::ShareHandleWithRemote(local_platform_file, remote_pid,
-                                            false);
+  return base::SharedMemory::DuplicateHandle(handle);
+#endif  // defined(OS_WIN) || defined(OS_MACOSX)
 }
 
 std::set<PP_Instance>* PpapiThread::GetGloballySeenInstanceIDSet() {
   return &globally_seen_instance_ids_;
 }
 
 IPC::Sender* PpapiThread::GetBrowserSender() {
   return this;
 }
 
@@ skipping 347 matching lines @@
       std::string("Plugin.Ppapi") + (is_broker_ ? "Broker" : "Plugin") +
       "LoadErrorCode_" + path.BaseName().MaybeAsASCII();
 
   // For sparse histograms, we can use the macro, as it does not incorporate a
   // static.
   UMA_HISTOGRAM_SPARSE_SLOWLY(histogram_name, error.code);
 #endif
 }
 
 }  // namespace content