End-to-end plumbing for dimming SDR layers

Model here is:
* HDR luminance is set to the current display brightness
* SDR luminance is set to the current SDR white point reported by
DisplayManager

Ideally we use scene-referred white points instead, so:
* PQ is always 10k nits
* HLG is always 1k nits
* Everything else is 150-200 nits

So relative dimming thresholds are fixed. But right now this is visually
less jarring (otherwise youtube UI will suddenly dim when autoplaying
HDR video).

Bug: 200310158
Test: Verified that plumbing sdr white point is sent to renderengine
Test: librenderengine_test
Test: libcompositionengine_test
Test: DataspaceUtils_test

Change-Id: I5bcea7941935c43e57cd5434e1ec69b41d31f2b4
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.h b/libs/renderengine/skia/SkiaGLRenderEngine.h
index 53792f9..a650313 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.h
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.h
@@ -106,12 +106,18 @@
     void initCanvas(SkCanvas* canvas, const DisplaySettings& display);
     void drawShadow(SkCanvas* canvas, const SkRRect& casterRRect,
                     const ShadowSettings& shadowSettings);
+
     // If requiresLinearEffect is true or the layer has a stretchEffect a new shader is returned.
     // Otherwise it returns the input shader.
-    sk_sp<SkShader> createRuntimeEffectShader(sk_sp<SkShader> shader, const LayerSettings& layer,
-                                              const DisplaySettings& display,
-                                              bool undoPremultipliedAlpha,
-                                              bool requiresLinearEffect);
+    struct RuntimeEffectShaderParameters {
+        sk_sp<SkShader> shader;
+        const LayerSettings& layer;
+        const DisplaySettings& display;
+        bool undoPremultipliedAlpha;
+        bool requiresLinearEffect;
+        float layerDimmingRatio;
+    };
+    sk_sp<SkShader> createRuntimeEffectShader(const RuntimeEffectShaderParameters&);
 
     EGLDisplay mEGLDisplay;
     EGLContext mEGLContext;