Refine dual-GPU detection on Mac OS X.

ui/gl/gpu_switching_manager.cc

Index: ui/gl/gpu_switching_manager.cc
diff --git a/ui/gl/gpu_switching_manager.cc b/ui/gl/gpu_switching_manager.cc
index 23fc2ffade4f86c1c6f4801196b448a997a1ea54..36ad7adde2ab26bd31c8628c5075511f5430c947 100644
--- a/ui/gl/gpu_switching_manager.cc
+++ b/ui/gl/gpu_switching_manager.cc
@@ -32,7 +32,6 @@ GpuSwitchingManager::GpuSwitchingManager()
       gpu_switching_option_set_(false),
       supports_dual_gpus_(false),
       supports_dual_gpus_set_(false),
-      gpu_count_(0),
       platform_specific_(new PlatformSpecific) {
 #if defined(OS_MACOSX)
   platform_specific_->discrete_pixel_format = nullptr;
@@ -91,7 +90,7 @@ bool GpuSwitchingManager::SupportsDualGpus() {
       // Browser process.
       // We only compute this flag in the browser process.
 #if defined(OS_MACOSX)
-      flag = (gpu_count_ == 2);
+      flag = (vendor_ids_.size() == 2);
       if (flag && command_line.HasSwitch(switches::kUseGL) &&
           command_line.GetSwitchValueASCII(switches::kUseGL) !=
             gfx::kGLImplementationDesktopName)
@@ -99,6 +98,17 @@ bool GpuSwitchingManager::SupportsDualGpus() {
 
       if (flag && !base::mac::IsOSLionOrLater())
         flag = false;
+
+      if (flag) {
+        // Only advertise that we have two GPUs to the rest of
+        // Chrome's code if we find an Intel GPU and some other
+        // vendor's GPU. Otherwise we don't understand the
+        // configuration and don't deal well with it (an example being
+        // the dual AMD GPUs in recent Mac Pros).
+        const uint32 intel = 0x8086;
+        flag = ((vendor_ids_[0] == intel && vendor_ids_[1] != intel) ||
+                (vendor_ids_[0] != intel && vendor_ids_[1] == intel));
+      }
 #endif  // OS_MACOSX
     }
     supports_dual_gpus_ = flag;
@@ -107,8 +117,9 @@ bool GpuSwitchingManager::SupportsDualGpus() {
   return supports_dual_gpus_;
 }
 
-void GpuSwitchingManager::SetGpuCount(size_t gpu_count) {
-  gpu_count_ = gpu_count;
+void GpuSwitchingManager::SetGpuVendorIds(
+    const std::vector<uint32>& vendor_ids) {
+  vendor_ids_ = vendor_ids;
 }
 
 void GpuSwitchingManager::AddObserver(GpuSwitchingObserver* observer) {