[mojo-edk] Fix lifetime management of rewritten Windows HANDLEs

mojo/edk/embedder/platform_handle.cc

Index: mojo/edk/embedder/platform_handle.cc
diff --git a/mojo/edk/embedder/platform_handle.cc b/mojo/edk/embedder/platform_handle.cc
index 5709b1e46850936b7ccff88e3b8f15313bf7bf21..b6b2cd22d1fee38d8f38879adda8d387a7f6a237 100644
--- a/mojo/edk/embedder/platform_handle.cc
+++ b/mojo/edk/embedder/platform_handle.cc
@@ -36,6 +36,32 @@ void PlatformHandle::CloseIfNecessary() {
   }
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 #elif defined(OS_WIN)
+  if (owning_process != base::GetCurrentProcessHandle()) {
+    // This handle may have been duplicated to a new target process but not yet
+    // sent there. In this case CloseHandle should NOT be called. From MSDN
+    // documentation for DuplicateHandle[1]:
+    //
+    //    Normally the target process closes a duplicated handle when that
+    //    process is finished using the handle. To close a duplicated handle
+    //    from the source process, call DuplicateHandle with the following
+    //    parameters:
+    //
+    //    * Set hSourceProcessHandle to the target process from the
+    //      call that created the handle.
+    //    * Set hSourceHandle to the duplicated handle to close.
+    //    * Set lpTargetHandle to NULL.
+    //    * Set dwOptions to DUPLICATE_CLOSE_SOURCE.
+    //
+    // [1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms724251
+    //
+    // NOTE: It's possible for this operation to fail if the owning process
+    // was terminated or is in the process of being terminated. Either way,
+    // there is nothing we can reasonably do about failure, so we ignore it.
+    DuplicateHandle(owning_process, handle, NULL, &handle, 0, FALSE,
+                    DUPLICATE_CLOSE_SOURCE);
+    return;
+  }
+
   bool success = !!CloseHandle(handle);
   DPCHECK(success);
   handle = INVALID_HANDLE_VALUE;