Do not lose secondary gpus and make sure to have an active gpu on multiple gpu configurations

content/gpu/gpu_main.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 <stddef.h>
 #include <stdlib.h>
 
 #include <memory>
 #include <utility>
 
@@ skipping 424 matching lines @@
       &gpu_info.gpu.vendor_id);
   DCHECK(success);
   success = base::HexStringToUInt(
       command_line.GetSwitchValueASCII(switches::kGpuDeviceID),
       &gpu_info.gpu.device_id);
   DCHECK(success);
   gpu_info.driver_vendor =
       command_line.GetSwitchValueASCII(switches::kGpuDriverVendor);
   gpu_info.driver_version =
       command_line.GetSwitchValueASCII(switches::kGpuDriverVersion);
+  gpu::ParseSecondaryGpuDevicesFromCommandLine(command_line, false, &gpu_info);
+  if (gpu_info.secondary_gpus.size() == 0)
+    gpu_info.gpu.active = true;

[Zhenyao Mo, 2016/04/21 17:03:37]

This is better, but still doesn't address the problem when multiple GPUs are
passed from browser process to GPU process, which one is active.  I suggest in
multiple GPU situation, you pass another switch to identify which GPU is active.
If you decide to pass all the information including secondary GPUs, it doesn't
make sense you leave out the "active" bit.

[Julien Isorce Samsung, 2016/04/21 23:27:08]

Done, I added kGpuActiveDeviceID.

+
   GetContentClient()->SetGpuInfo(gpu_info);
 }
 
 bool WarmUpSandbox(const base::CommandLine& command_line) {
   {
     TRACE_EVENT0("gpu", "Warm up rand");
     // Warm up the random subsystem, which needs to be done pre-sandbox on all
     // platforms.
     (void) base::RandUint64();
   }
@@ skipping 130 matching lines @@
     return true;
   }
 
   return false;
 }
 #endif  // defined(OS_WIN)
 
 }  // namespace.
 
 }  // namespace content