clang/win: Enable -Wswitch.

content/browser/gpu/gpu_data_manager_impl_private.cc

Index: content/browser/gpu/gpu_data_manager_impl_private.cc
diff --git a/content/browser/gpu/gpu_data_manager_impl_private.cc b/content/browser/gpu/gpu_data_manager_impl_private.cc
index 6fa3568da44e2af3d781dd10358d74d5e7f83fc7..03850027d86a93ec816643babeb57be4b2a662de 100644
--- a/content/browser/gpu/gpu_data_manager_impl_private.cc
+++ b/content/browser/gpu/gpu_data_manager_impl_private.cc
@@ -99,6 +99,9 @@ int GetGpuBlacklistHistogramValueWin(GpuFeatureStatus status) {
     case kGpuFeatureDisabled:
       entry_index += 2;
       break;
+    case kGpuFeatureNumStatus:
+      NOTREACHED();
+      break;
   }
   return entry_index;
 }