Add support for background blurs

Bug: 141640413
Fixes: 146384234
Test: adb shell setprop debug.sf.disableBlurs 1
Test: adb shell setprop debug.sf.gaussianBlur 0
Test: adb shell setprop ro.surface_flinger.supports_background_blur 1
Test: ./SurfaceFlinger_test --gtest_filter=Layer*Tests/Layer*Test.SetBackgroundBlur*
Test: ./librenderengine_test --gtest_filter=*BlurBackground*"
Test: atest SurfaceFlinger_test:SurfaceInterceptorTest#InterceptBackgroundBlurRadiusUpdateWorks
Change-Id: I5194c910fe7062f33e70943867012539e6c6626a
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
index a64fdbf..3dbd25e 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/LayerFECompositionState.h
@@ -63,6 +63,9 @@
     // The alpha value for this layer
     float alpha{1.f};
 
+    // Background blur in pixels
+    int backgroundBlurRadius{0};
+
     // The transform from layer local coordinates to composition coordinates
     ui::Transform geomLayerTransform;
 
diff --git a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Output.h b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Output.h
index 159e928..3a9776d 100644
--- a/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Output.h
+++ b/services/surfaceflinger/CompositionEngine/include/compositionengine/impl/Output.h
@@ -116,6 +116,7 @@
 
 private:
     void dirtyEntireOutput();
+    compositionengine::OutputLayer* findLayerRequestingBackgroundComposition() const;
     ui::Dataspace getBestDataspace(ui::Dataspace*, bool*) const;
     compositionengine::Output::ColorProfile pickColorProfile(
             const compositionengine::CompositionRefreshArgs&) const;
@@ -126,6 +127,7 @@
     std::unique_ptr<compositionengine::RenderSurface> mRenderSurface;
 
     ReleasedLayers mReleasedLayers;
+    OutputLayer* mLayerRequestingBackgroundBlur = nullptr;
 };
 
 // This template factory function standardizes the implementation details of the