Refactor HWUI readback code to be backend independent

Implement readback from Surface, TextureView and HW Bitmap
for Vulkan pipeline by wrapping the graphics buffer in an SkImage.
Refactor both Vulkan and GL readback to use common code.
TextureView readback is moved from IRenderPipeline interface to
Readback class. Refactor all 3 readback flows to use common
implementation.

Test: Passed all view, uirendering and graphics CTS tests with GL
Test: Passed many CTS test with Vulkan, that require readback
Bug: 113673613
Change-Id: Ifbfd8170a5401f87a709b4b1b9fa058e8e11768d
diff --git a/libs/hwui/renderthread/RenderThread.cpp b/libs/hwui/renderthread/RenderThread.cpp
index 2322fbf..7258a0a 100644
--- a/libs/hwui/renderthread/RenderThread.cpp
+++ b/libs/hwui/renderthread/RenderThread.cpp
@@ -19,13 +19,12 @@
 #include "CanvasContext.h"
 #include "DeviceInfo.h"
 #include "EglManager.h"
+#include "Readback.h"
 #include "RenderProxy.h"
 #include "VulkanManager.h"
 #include "hwui/Bitmap.h"
 #include "pipeline/skia/SkiaOpenGLPipeline.h"
-#include "pipeline/skia/SkiaOpenGLReadback.h"
 #include "pipeline/skia/SkiaVulkanPipeline.h"
-#include "pipeline/skia/SkiaVulkanReadback.h"
 #include "renderstate/RenderState.h"
 #include "utils/FatVector.h"
 #include "utils/TimeUtils.h"
@@ -235,18 +234,7 @@
 
 Readback& RenderThread::readback() {
     if (!mReadback) {
-        auto renderType = Properties::getRenderPipelineType();
-        switch (renderType) {
-            case RenderPipelineType::SkiaGL:
-                mReadback = new skiapipeline::SkiaOpenGLReadback(*this);
-                break;
-            case RenderPipelineType::SkiaVulkan:
-                mReadback = new skiapipeline::SkiaVulkanReadback(*this);
-                break;
-            default:
-                LOG_ALWAYS_FATAL("canvas context type %d not supported", (int32_t)renderType);
-                break;
-        }
+        mReadback = new Readback(*this);
     }
 
     return *mReadback;