Default initialize DeviceDescriptor in DawnTest.cpp

Bug: dawn:1120
Change-Id: I6cd2e9072e3579891793d2a352421a14d5ed0b89
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/64662
Auto-Submit: Austin Eng <enga@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>
diff --git a/src/tests/DawnTest.cpp b/src/tests/DawnTest.cpp
index 5e323a6..23d9433 100644
--- a/src/tests/DawnTest.cpp
+++ b/src/tests/DawnTest.cpp
@@ -909,7 +909,7 @@
     for (const char* forceDisabledWorkaround : mParam.forceDisabledWorkarounds) {
         ASSERT(gTestEnv->GetInstance()->GetToggleInfo(forceDisabledWorkaround) != nullptr);
     }
-    dawn_native::DeviceDescriptor deviceDescriptor;
+    dawn_native::DeviceDescriptor deviceDescriptor = {};
     deviceDescriptor.forceEnabledToggles = mParam.forceEnabledWorkarounds;
     deviceDescriptor.forceDisabledToggles = mParam.forceDisabledWorkarounds;
     deviceDescriptor.requiredExtensions = GetRequiredExtensions();