Various new metal fixes (#1465)

* - Fix the second window related tabbing issue
- Merge calls to UseResoources acrooaa all the SRGs
- Move SamplerCache to the device to ensure only one cache to reduce duplication
- Fixes to compute threading numbers getting reset to 0,0,0
- Cleanup withing BufferPoolResolver
- Argument buffers are now queued to be cleaned up upon shutdown

Gems/Atom/RPI/Code/Include/Atom/RPI.Public/Pass/Specific/DownsampleMipChainPass.h

@@ -30,6 +30,7 @@ namespace AZ
         //! It does this by recursively creating Compute Passes to write to each mip using the Compute Shader.
         class DownsampleMipChainPass
             : public ParentPass
+            , private ShaderReloadNotificationBus::Handler
         {
             AZ_RPI_PASS(DownsampleMipChainPass);
 
@@ -39,6 +40,7 @@ namespace AZ
           
             //! Creates a new pass without a PassTemplate
             static Ptr<DownsampleMipChainPass> Create(const PassDescriptor& descriptor);
+            virtual ~DownsampleMipChainPass();
             
         protected:
             explicit DownsampleMipChainPass(const PassDescriptor& descriptor);
@@ -49,6 +51,11 @@ namespace AZ
             void BuildInternal() override;
             void FrameBeginInternal(FramePrepareParams params) override;
 
+            // ShaderReloadNotificationBus::Handler overrides...
+            void OnShaderReinitialized(const Shader& shader) override;
+            void OnShaderAssetReinitialized(const Data::Asset<ShaderAsset>& shaderAsset) override;
+            void OnShaderVariantReinitialized(const ShaderVariant& shaderVariant) override;
+            
         private:
 
             // Gets target height, width and mip levels from the input/output image attachment

Gems/Atom/RPI/Code/Source/RPI.Public/Pass/Specific/DownsampleMipChainPass.cpp

@@ -54,8 +54,14 @@ namespace AZ
             }
 
             m_passData = *passData;
+            ShaderReloadNotificationBus::Handler::BusConnect(passData->m_shaderReference.m_assetId);
         }
 
+        DownsampleMipChainPass::~DownsampleMipChainPass()
+        {
+            ShaderReloadNotificationBus::Handler::BusDisconnect();
+        }
+    
         void DownsampleMipChainPass::ResetInternal()
         {
             RemoveChildren();
@@ -206,5 +212,19 @@ namespace AZ
             ParentPass::FrameBeginInternal(params);
         }
 
+        void DownsampleMipChainPass::OnShaderReinitialized([[maybe_unused]] const Shader& shader)
+        {
+            m_needToUpdateChildren = true;
+        }
+    
+        void DownsampleMipChainPass::OnShaderAssetReinitialized([[maybe_unused]] const Data::Asset<ShaderAsset>& shaderAsset)
+        {
+            m_needToUpdateChildren = true;
+        }
+    
+        void DownsampleMipChainPass::OnShaderVariantReinitialized([[maybe_unused]] const ShaderVariant& shaderVariant)
+        {
+            m_needToUpdateChildren = true;
+        }
     }   // namespace RPI
 }   // namespace AZ