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/libs/renderengine/gl/GLESRenderEngine.h b/libs/renderengine/gl/GLESRenderEngine.h
index f41eda2..547235a 100644
--- a/libs/renderengine/gl/GLESRenderEngine.h
+++ b/libs/renderengine/gl/GLESRenderEngine.h
@@ -46,6 +46,7 @@
 namespace gl {
 
 class GLImage;
+class BlurFilter;
 
 class GLESRenderEngine : public impl::RenderEngine {
 public:
@@ -117,6 +118,7 @@
     std::unique_ptr<Framebuffer> createFramebuffer();
     std::unique_ptr<Image> createImage();
     void checkErrors() const;
+    void checkErrors(const char* tag) const;
     void setScissor(const Rect& region);
     void disableScissor();
     bool waitSync(EGLSyncKHR sync, EGLint flags);
@@ -228,6 +230,9 @@
 
     std::unique_ptr<Framebuffer> mDrawingBuffer;
 
+    // Blur effect processor, only instantiated when a layer requests it.
+    BlurFilter* mBlurFilter = nullptr;
+
     class FlushTracer {
     public:
         FlushTracer(GLESRenderEngine* engine);
@@ -251,6 +256,11 @@
     };
     friend class FlushTracer;
     friend class ImageManager;
+    friend class GLFramebuffer;
+    friend class BlurFilter;
+    friend class GaussianBlurFilter;
+    friend class LensBlurFilter;
+    friend class GenericProgram;
     std::unique_ptr<FlushTracer> mFlushTracer;
     std::unique_ptr<ImageManager> mImageManager = std::make_unique<ImageManager>(this);
 };