Add the webgpu.h swapchain creation path

This commit changes wgpu::Device::CreateSwapChain to take an additional
wgpu::Surface argument. Passing nullptr is enough to stay on the
previous swapchain implementation, until the new one is ready.

In order to support both the "old" implementation-based swapchains and
the "new" surface-based swapchains. SwapChainBase is now split into
three abstract classes:

 - SwapChainBase that has a virtual method for each of the
wgpu::SwapChain methods.
 - OldSwapChainBase that corresponds to the implementation-based
swapchains.
 - NewSwapChainBase that will contain the surface-based swapchain
implementation and will eventually just be renamed to SwapChainBase.

The interaction of the surface-based swapchains with the Surface objects
aren't implemented yet, neither are the swapchain methods. Only creation
works.

Validation tests for surface-based swapchain creation are added in the
end2end test target because they need to create OS windows.

Bug: dawn:269

Change-Id: I7e07d6c666479867b9a16d7b1b8c181d5dbd69a0
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/15281
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>

src/fuzzers/DawnWireServerFuzzer.cpp

@@ -49,13 +49,15 @@ namespace {
     std::string sInjectedErrorTestcaseOutDir;
     uint64_t sOutputFileNumber = 0;
 
-    WGPUSwapChain ErrorDeviceCreateSwapChain(WGPUDevice device, const WGPUSwapChainDescriptor*) {
+    WGPUSwapChain ErrorDeviceCreateSwapChain(WGPUDevice device,
+                                             WGPUSurface surface,
+                                             const WGPUSwapChainDescriptor*) {
         WGPUSwapChainDescriptor desc;
         desc.nextInChain = nullptr;
         desc.label = nullptr;
         // A 0 implementation will trigger a swapchain creation error.
         desc.implementation = 0;
-        return sOriginalDeviceCreateSwapChain(device, &desc);
+        return sOriginalDeviceCreateSwapChain(device, surface, &desc);
     }
 
 }  // namespace