Fix WebView interop mode with Vulkan hwui

This CL fixes two problems with WebView/SkiaRenderer/GL with vulkan hwui:
* Missing allocator, chrome introduced one to use single instance with Skia.
* Wrong fboid for query alpha capabilities.

Bug: 984955
Change-Id: Ib8e9fb57bcf9b11557aac5a412abb91556819038
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2314419Reviewed-by: Peng Huang <penghuang@chromium.org>
Commit-Queue: Vasiliy Telezhnikov <vasilyt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791036}

android_webview/browser/gfx/BUILD.gn

@@ -89,6 +89,7 @@ source_set("gfx") {
     "//gpu/skia_bindings",
     "//gpu/vulkan:vulkan",
     "//gpu/vulkan/init",
+    "//gpu/vulkan/init:skia",
     "//services/viz/privileged/mojom",
     "//services/viz/public/mojom",
     "//skia",

android_webview/browser/gfx/aw_vulkan_context_provider.cc

@@ -12,6 +12,7 @@
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/native_library.h"
+#include "gpu/vulkan/init/gr_vk_memory_allocator_impl.h"
 #include "gpu/vulkan/init/vulkan_factory.h"
 #include "gpu/vulkan/vulkan_device_queue.h"
 #include "gpu/vulkan/vulkan_fence_helper.h"
@@ -173,7 +174,7 @@ bool AwVulkanContextProvider::Initialize(AwDrawFn_InitVkParams* params) {
       .fVkExtensions = &vk_extensions,
       .fDeviceFeatures = params->device_features,
       .fDeviceFeatures2 = params->device_features_2,
-      .fMemoryAllocator = nullptr,
+      .fMemoryAllocator = gpu::CreateGrVkMemoryAllocator(device_queue_.get()),
       .fGetProc = get_proc,
       .fOwnsInstanceAndDevice = false,
   };

components/viz/service/display_embedder/skia_output_device_webview.cc

@@ -37,7 +37,8 @@ SkiaOutputDeviceWebView::SkiaOutputDeviceWebView(
   DCHECK(context_state_->context());
 
   // Get alpha bits from the default frame buffer.
-  glBindFramebufferEXT(GL_FRAMEBUFFER, 0);
+  glBindFramebufferEXT(GL_FRAMEBUFFER,
+                       gl_surface_->GetBackingFramebufferObject());
   context_state_->gr_context()->resetContext(kRenderTarget_GrGLBackendState);
   GLint alpha_bits = 0;
   glGetIntegerv(GL_ALPHA_BITS, &alpha_bits);

gpu/vulkan/vulkan_device_queue.cc

@@ -291,6 +291,9 @@ bool VulkanDeviceQueue::InitializeForWebView(
   vk_queue_index_ = vk_queue_index;
   enabled_extensions_ = std::move(enabled_extensions);
 
+  vma::CreateAllocator(vk_physical_device_, vk_device_, vk_instance_,
+                       &vma_allocator_);
+
   cleanup_helper_ = std::make_unique<VulkanFenceHelper>(this);
   return true;
 }