Fix out-of-bounds access bug in ANGLE tests

src/gpu_info_util/SystemInfo.h

@@ -59,8 +59,9 @@ struct SystemInfo
     std::vector<GPUDeviceInfo> gpus;
 
     // Index of the GPU expected to be used for 3D graphics. Based on a best-guess heuristic on
-    // some platforms. On windows, this is accurate.
-    int activeGPUIndex = -1;
+    // some platforms. On Windows, this is accurate. Note `gpus` must be checked for empty before
+    // indexing.
+    int activeGPUIndex = 0;
 
     bool isOptimus       = false;
     bool isAMDSwitchable = false;

src/tests/gl_tests/DrawBaseVertexBaseInstanceTest.cpp

@@ -541,7 +541,7 @@ TEST_P(DrawBaseVertexBaseInstanceTest, DrawArraysInstancedBaseInstance)
     if (IsAMD() && IsWindows() && IsDesktopOpenGL())
     {
         SystemInfo *systemInfo = GetTestSystemInfo();
-        if (!(systemInfo->activeGPUIndex < 0 || systemInfo->gpus.empty()))
+        if (!systemInfo->gpus.empty())
         {
             ANGLE_SKIP_TEST_IF(0x6613 == systemInfo->gpus[systemInfo->activeGPUIndex].deviceId);
         }

src/tests/test_expectations/GPUTestConfig.cpp

@@ -351,13 +351,7 @@ inline bool GetActiveGPU(GPUDeviceInfo **devInfo)
     {
         return false;
     }
-    // Default to the first index
-    uint32_t index = 0;
-    // See if the activeGPUIndex was set first
-    if (systemInfo->activeGPUIndex != -1)
-    {
-        index = systemInfo->activeGPUIndex;
-    }
+    uint32_t index = systemInfo->activeGPUIndex;
     ASSERT(index < systemInfo->gpus.size());
     *devInfo = &(systemInfo->gpus[index]);
     return true;

src/tests/test_utils/angle_test_instantiate.cpp

@@ -96,7 +96,7 @@ bool HasSystemVendorID(VendorID vendorID)
 {
     SystemInfo *systemInfo = GetTestSystemInfo();
     // Unfortunately sometimes GPU info collection can fail.
-    if (systemInfo->activeGPUIndex < 0 || systemInfo->gpus.empty())
+    if (systemInfo->gpus.empty())
     {
         return false;
     }