Add Instance and CreateInstance to webgpu.h

This is the first step in making the API before WGPUDevice creation
match webgpu.h and is necessary to implement WGPUSwapChain.

BUG=dawn:269

Change-Id: If92ced42d7683d79e67c02738949ff8b483d22c4
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14061
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kai Ninomiya <kainino@chromium.org>

src/dawn_native/DawnNative.cpp

@@ -80,12 +80,14 @@ namespace dawn_native {
 
     // Instance
 
-    Instance::Instance() : mImpl(new InstanceBase()) {
+    Instance::Instance() : mImpl(InstanceBase::Create()) {
     }
 
     Instance::~Instance() {
-        delete mImpl;
-        mImpl = nullptr;
+        if (mImpl != nullptr) {
+            mImpl->Release();
+            mImpl = nullptr;
+        }
     }
 
     void Instance::DiscoverDefaultAdapters() {
@@ -121,6 +123,10 @@ namespace dawn_native {
         mImpl->SetPlatform(platform);
     }
 
+    WGPUInstance Instance::Get() const {
+        return reinterpret_cast<WGPUInstance>(mImpl);
+    }
+
     size_t GetLazyClearCountForTesting(WGPUDevice device) {
         dawn_native::DeviceBase* deviceBase = reinterpret_cast<dawn_native::DeviceBase*>(device);
         return deviceBase->GetLazyClearCountForTesting();

src/dawn_native/Instance.cpp

@@ -50,6 +50,19 @@ namespace dawn_native {
 
     // InstanceBase
 
+    // static
+    InstanceBase* InstanceBase::Create(const InstanceDescriptor* descriptor) {
+        Ref<InstanceBase> instance = AcquireRef(new InstanceBase);
+        if (!instance->Initialize(descriptor)) {
+            return nullptr;
+        }
+        return instance.Detach();
+    }
+
+    bool InstanceBase::Initialize(const InstanceDescriptor*) {
+        return true;
+    }
+
     void InstanceBase::DiscoverDefaultAdapters() {
         EnsureBackendConnections();
 

src/dawn_native/Instance.h

@@ -18,7 +18,9 @@
 #include "dawn_native/Adapter.h"
 #include "dawn_native/BackendConnection.h"
 #include "dawn_native/Extensions.h"
+#include "dawn_native/RefCounted.h"
 #include "dawn_native/Toggles.h"
+#include "dawn_native/dawn_platform.h"
 
 #include <array>
 #include <memory>
@@ -29,13 +31,9 @@ namespace dawn_native {
 
     // This is called InstanceBase for consistency across the frontend, even if the backends don't
     // specialize this class.
-    class InstanceBase final {
+    class InstanceBase final : public RefCounted {
       public:
-        InstanceBase() = default;
-        ~InstanceBase() = default;
-
-        InstanceBase(const InstanceBase& other) = delete;
-        InstanceBase& operator=(const InstanceBase& other) = delete;
+        static InstanceBase* Create(const InstanceDescriptor* descriptor = nullptr);
 
         void DiscoverDefaultAdapters();
         bool DiscoverAdapters(const AdapterDiscoveryOptionsBase* options);
@@ -67,6 +65,14 @@ namespace dawn_native {
         dawn_platform::Platform* GetPlatform() const;
 
       private:
+        InstanceBase() = default;
+        ~InstanceBase() = default;
+
+        InstanceBase(const InstanceBase& other) = delete;
+        InstanceBase& operator=(const InstanceBase& other) = delete;
+
+        bool Initialize(const InstanceDescriptor* descriptor);
+
         // Lazily creates connections to all backends that have been compiled.
         void EnsureBackendConnections();
 

src/include/dawn_native/DawnNative.h

@@ -146,6 +146,9 @@ namespace dawn_native {
 
         void SetPlatform(dawn_platform::Platform* platform);
 
+        // Returns the underlying WGPUInstance object.
+        WGPUInstance Get() const;
+
       private:
         InstanceBase* mImpl = nullptr;
     };

src/tests/unittests/ExtensionTests.cpp

@@ -20,7 +20,10 @@
 
 class ExtensionTests : public testing::Test {
   public:
-    ExtensionTests() : testing::Test(), mInstanceBase(), mAdapterBase(&mInstanceBase) {
+    ExtensionTests()
+        : testing::Test(),
+          mInstanceBase(dawn_native::InstanceBase::Create()),
+          mAdapterBase(mInstanceBase.Get()) {
     }
 
     std::vector<const char*> GetAllExtensionNames() {
@@ -35,7 +38,7 @@ class ExtensionTests : public testing::Test {
         static_cast<size_t>(dawn_native::Extension::EnumCount);
 
   protected:
-    dawn_native::InstanceBase mInstanceBase;
+    dawn_native::Ref<dawn_native::InstanceBase> mInstanceBase;
     dawn_native::null::Adapter mAdapterBase;
 };
 

src/tests/unittests/GetProcAddressTests.cpp

@@ -51,8 +51,8 @@ namespace {
       public:
         GetProcAddressTests()
             : testing::TestWithParam<DawnFlavor>(),
-              mNativeInstance(),
-              mNativeAdapter(&mNativeInstance) {
+              mNativeInstance(dawn_native::InstanceBase::Create()),
+              mNativeAdapter(mNativeInstance.Get()) {
         }
 
         void SetUp() override {
@@ -90,7 +90,7 @@ namespace {
         }
 
       protected:
-        dawn_native::InstanceBase mNativeInstance;
+        dawn_native::Ref<dawn_native::InstanceBase> mNativeInstance;
         dawn_native::null::Adapter mNativeAdapter;
 
         std::unique_ptr<utils::TerribleCommandBuffer> mC2sBuf;
@@ -136,13 +136,17 @@ namespace {
         ASSERT_EQ(mProcs.getProcAddress(mDevice.Get(), "0"), nullptr);
     }
 
-    // Test that GetProcAddress supports itself: it is handled specially because it is a
-    // freestanding function and not a method on an object.
-    TEST_P(GetProcAddressTests, GetProcAddressItself) {
+    // Test that GetProcAddress supports freestanding function that are handled specially
+    TEST_P(GetProcAddressTests, FreeStandingFunctions) {
         ASSERT_EQ(mProcs.getProcAddress(nullptr, "wgpuGetProcAddress"),
                   reinterpret_cast<WGPUProc>(mProcs.getProcAddress));
         ASSERT_EQ(mProcs.getProcAddress(mDevice.Get(), "wgpuGetProcAddress"),
                   reinterpret_cast<WGPUProc>(mProcs.getProcAddress));
+
+        ASSERT_EQ(mProcs.getProcAddress(nullptr, "wgpuCreateInstance"),
+                  reinterpret_cast<WGPUProc>(mProcs.createInstance));
+        ASSERT_EQ(mProcs.getProcAddress(mDevice.Get(), "wgpuCreateInstance"),
+                  reinterpret_cast<WGPUProc>(mProcs.createInstance));
     }
 
     INSTANTIATE_TEST_SUITE_P(,