[Impeller] Make DeviceHolder follow convention for backend specific utilities.

Utilities below the HAL that are backend specific have the VK (in case
of Vulkan) suffix. The only class that doesn't follow this convention
is/was DeviceHolder. This caused some confusion when reading code
leading to wondering what a device holder above the HAL was supposed to
do/mean. Adds the VK suffix to device holder with a docstring. Also adds
the file the source set as it was missing.

No change in functionality. Just a rename of an existing class.

Author: chinmaygarde

ci/licenses_golden/licenses_flutter

@@ -38103,7 +38103,7 @@ ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/descriptor_pool_vk.cc
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/descriptor_pool_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/device_buffer_vk.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/device_buffer_vk.h + ../../../flutter/LICENSE
-ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/device_holder.h + ../../../flutter/LICENSE
+ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/device_holder_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/fence_waiter_vk.cc + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/fence_waiter_vk.h + ../../../flutter/LICENSE
 ORIGIN: ../../../flutter/impeller/renderer/backend/vulkan/formats_vk.cc + ../../../flutter/LICENSE
@@ -40954,7 +40954,7 @@ FILE: ../../../flutter/impeller/renderer/backend/vulkan/descriptor_pool_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/descriptor_pool_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/device_buffer_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/device_buffer_vk.h
-FILE: ../../../flutter/impeller/renderer/backend/vulkan/device_holder.h
+FILE: ../../../flutter/impeller/renderer/backend/vulkan/device_holder_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/fence_waiter_vk.cc
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/fence_waiter_vk.h
 FILE: ../../../flutter/impeller/renderer/backend/vulkan/formats_vk.cc

impeller/renderer/backend/vulkan/BUILD.gn

@@ -64,6 +64,7 @@ impeller_component("vulkan") {
     "descriptor_pool_vk.h",
     "device_buffer_vk.cc",
     "device_buffer_vk.h",
+    "device_holder_vk.h",
     "fence_waiter_vk.cc",
     "fence_waiter_vk.h",
     "formats_vk.cc",

impeller/renderer/backend/vulkan/allocator_vk.cc

@@ -94,7 +94,7 @@ static PoolVMA CreateBufferPool(VmaAllocator allocator) {
 AllocatorVK::AllocatorVK(std::weak_ptr<Context> context,
                          uint32_t vulkan_api_version,
                          const vk::PhysicalDevice& physical_device,
-                         const std::shared_ptr<DeviceHolder>& device_holder,
+                         const std::shared_ptr<DeviceHolderVK>& device_holder,
                          const vk::Instance& instance,
                          const CapabilitiesVK& capabilities)
     : context_(std::move(context)), device_holder_(device_holder) {

impeller/renderer/backend/vulkan/allocator_vk.h

@@ -10,7 +10,7 @@
 #include "impeller/core/allocator.h"
 #include "impeller/renderer/backend/vulkan/context_vk.h"
 #include "impeller/renderer/backend/vulkan/device_buffer_vk.h"
-#include "impeller/renderer/backend/vulkan/device_holder.h"
+#include "impeller/renderer/backend/vulkan/device_holder_vk.h"
 #include "impeller/renderer/backend/vulkan/vk.h"
 
 #include <array>
@@ -33,7 +33,7 @@ class AllocatorVK final : public Allocator {
   UniqueAllocatorVMA allocator_;
   UniquePoolVMA staging_buffer_pool_;
   std::weak_ptr<Context> context_;
-  std::weak_ptr<DeviceHolder> device_holder_;
+  std::weak_ptr<DeviceHolderVK> device_holder_;
   ISize max_texture_size_;
   bool is_valid_ = false;
   bool supports_memoryless_textures_ = false;
@@ -44,7 +44,7 @@ class AllocatorVK final : public Allocator {
   AllocatorVK(std::weak_ptr<Context> context,
               uint32_t vulkan_api_version,
               const vk::PhysicalDevice& physical_device,
-              const std::shared_ptr<DeviceHolder>& device_holder,
+              const std::shared_ptr<DeviceHolderVK>& device_holder,
               const vk::Instance& instance,
               const CapabilitiesVK& capabilities);
 

impeller/renderer/backend/vulkan/command_encoder_vk.cc

@@ -66,7 +66,7 @@ std::shared_ptr<CommandEncoderVK> CommandEncoderFactoryVK::Create() {
 }
 
 CommandEncoderVK::CommandEncoderVK(
-    std::weak_ptr<const DeviceHolder> device_holder,
+    std::weak_ptr<const DeviceHolderVK> device_holder,
     std::shared_ptr<TrackedObjectsVK> tracked_objects,
     const std::shared_ptr<QueueVK>& queue,
     std::shared_ptr<FenceWaiterVK> fence_waiter)

impeller/renderer/backend/vulkan/command_encoder_vk.h

@@ -13,7 +13,7 @@
 #include "impeller/renderer/backend/vulkan/command_queue_vk.h"
 #include "impeller/renderer/backend/vulkan/context_vk.h"
 #include "impeller/renderer/backend/vulkan/descriptor_pool_vk.h"
-#include "impeller/renderer/backend/vulkan/device_holder.h"
+#include "impeller/renderer/backend/vulkan/device_holder_vk.h"
 #include "impeller/renderer/backend/vulkan/queue_vk.h"
 #include "impeller/renderer/backend/vulkan/shared_object_vk.h"
 #include "impeller/renderer/backend/vulkan/vk.h"
@@ -52,7 +52,7 @@ class CommandEncoderVK {
   using SubmitCallback = std::function<void(bool)>;
 
   // Visible for testing.
-  CommandEncoderVK(std::weak_ptr<const DeviceHolder> device_holder,
+  CommandEncoderVK(std::weak_ptr<const DeviceHolderVK> device_holder,
                    std::shared_ptr<TrackedObjectsVK> tracked_objects,
                    const std::shared_ptr<QueueVK>& queue,
                    std::shared_ptr<FenceWaiterVK> fence_waiter);
@@ -91,7 +91,7 @@ class CommandEncoderVK {
   friend class ContextVK;
   friend class CommandQueueVK;
 
-  std::weak_ptr<const DeviceHolder> device_holder_;
+  std::weak_ptr<const DeviceHolderVK> device_holder_;
   std::shared_ptr<TrackedObjectsVK> tracked_objects_;
   std::shared_ptr<QueueVK> queue_;
   const std::shared_ptr<FenceWaiterVK> fence_waiter_;

impeller/renderer/backend/vulkan/compute_pipeline_vk.cc

@@ -7,7 +7,7 @@
 namespace impeller {
 
 ComputePipelineVK::ComputePipelineVK(
-    std::weak_ptr<DeviceHolder> device_holder,
+    std::weak_ptr<DeviceHolderVK> device_holder,
     std::weak_ptr<PipelineLibrary> library,
     const ComputePipelineDescriptor& desc,
     vk::UniquePipeline pipeline,
@@ -22,7 +22,7 @@ ComputePipelineVK::ComputePipelineVK(
 }
 
 ComputePipelineVK::~ComputePipelineVK() {
-  std::shared_ptr<DeviceHolder> device_holder = device_holder_.lock();
+  std::shared_ptr<DeviceHolderVK> device_holder = device_holder_.lock();
   if (device_holder) {
     descriptor_set_layout_.reset();
     layout_.reset();

impeller/renderer/backend/vulkan/compute_pipeline_vk.h

@@ -9,7 +9,7 @@
 
 #include "flutter/fml/macros.h"
 #include "impeller/base/backend_cast.h"
-#include "impeller/renderer/backend/vulkan/device_holder.h"
+#include "impeller/renderer/backend/vulkan/device_holder_vk.h"
 #include "impeller/renderer/backend/vulkan/vk.h"
 #include "impeller/renderer/pipeline.h"
 
@@ -20,7 +20,7 @@ class ComputePipelineVK final
       public BackendCast<ComputePipelineVK,
                          Pipeline<ComputePipelineDescriptor>> {
  public:
-  ComputePipelineVK(std::weak_ptr<DeviceHolder> device_holder,
+  ComputePipelineVK(std::weak_ptr<DeviceHolderVK> device_holder,
                     std::weak_ptr<PipelineLibrary> library,
                     const ComputePipelineDescriptor& desc,
                     vk::UniquePipeline pipeline,
@@ -39,7 +39,7 @@ class ComputePipelineVK final
  private:
   friend class PipelineLibraryVK;
 
-  std::weak_ptr<DeviceHolder> device_holder_;
+  std::weak_ptr<DeviceHolderVK> device_holder_;
   vk::UniquePipeline pipeline_;
   vk::UniquePipelineLayout layout_;
   vk::UniqueDescriptorSetLayout descriptor_set_layout_;

impeller/renderer/backend/vulkan/context_vk.h

@@ -14,7 +14,7 @@
 #include "impeller/base/backend_cast.h"
 #include "impeller/core/formats.h"
 #include "impeller/renderer/backend/vulkan/command_pool_vk.h"
-#include "impeller/renderer/backend/vulkan/device_holder.h"
+#include "impeller/renderer/backend/vulkan/device_holder_vk.h"
 #include "impeller/renderer/backend/vulkan/pipeline_library_vk.h"
 #include "impeller/renderer/backend/vulkan/queue_vk.h"
 #include "impeller/renderer/backend/vulkan/sampler_library_vk.h"
@@ -130,7 +130,7 @@ class ContextVK final : public Context,
     return true;
   }
 
-  std::shared_ptr<DeviceHolder> GetDeviceHolder() const {
+  std::shared_ptr<DeviceHolderVK> GetDeviceHolder() const {
     return device_holder_;
   }
 
@@ -164,7 +164,7 @@ class ContextVK final : public Context,
   void InitializeCommonlyUsedShadersIfNeeded() const override;
 
  private:
-  struct DeviceHolderImpl : public DeviceHolder {
+  struct DeviceHolderImpl : public DeviceHolderVK {
     // |DeviceHolder|
     const vk::Device& GetDevice() const override { return device.get(); }
     // |DeviceHolder|