Add CHECK on file descriptor in various IPC::ChannelHandle passed in.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index 6b9933a730fd22cc4c6eafaeb944969f4da90434..cb924802f68ea4f569430a111fe6f443bf4b48b6 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -798,6 +798,12 @@ GpuChannelHost* RenderThreadImpl::EstablishGpuChannelSync(
     return NULL;
   }
 
+#if defined(OS_POSIX)
+  // Check the validity of fd for bug investigation.  Replace with normal error
+  // handling (see above) after bug fixed. See for details: crbug.com/95732.
+  CHECK_NE(-1, channel_handle.socket.fd);
+#endif
+
   gpu_channel_->set_gpu_info(gpu_info);
   content::GetContentClient()->SetGpuInfo(gpu_info);