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_info.gpu.active = true;

[Zhenyao Mo, 2016/04/19 21:05:27]

Why assume the primary GPU is active? Wouldn't this be incorrect in some
situations?

[Julien Isorce Samsung, 2016/04/20 17:19:21]

You are right. When there is least one secondary gpu the active gpu will be
identified by gpu::IdentifyActiveGPU (assuming that function succeeds).
gpu::IdentifyActiveGPU will be called from "CollectGraphicsInfo" (some lines
above, i.e. l307)

But when there is no secondary gpu, gpu::IdentifyActiveGPU does an early return
so gpu_info.gpu.active is false (default value). I do not think it is a problem
for black list or workarounds when there is only one gpu but that's is
disturbing that active is false.

I'll change this to set it to true only if gpu_info.secondary_gpus.size() == 0

+  gpu::ParseSecondaryGpuDevicesFromCommandLine(
+      command_line, switches::kGpuSecondaryVendorIDs,
+      switches::kGpuSecondaryDeviceIDs, &gpu_info);
+
   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