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/cmds/surfacereplayer/proto/src/trace.proto b/cmds/surfacereplayer/proto/src/trace.proto
index 7f2f949..b574098 100644
--- a/cmds/surfacereplayer/proto/src/trace.proto
+++ b/cmds/surfacereplayer/proto/src/trace.proto
@@ -51,6 +51,7 @@
         RelativeParentChange        relative_parent         = 18;
         DetachChildrenChange        detach_children         = 19;
         ReparentChildrenChange      reparent_children       = 20;
+        BackgroundBlurRadiusChange  background_blur_radius  = 21;
         ShadowRadiusChange          shadow_radius           = 22;
     }
 }
@@ -73,6 +74,10 @@
     required float corner_radius = 1;
 }
 
+message BackgroundBlurRadiusChange {
+    required float background_blur_radius = 1;
+}
+
 message LayerChange {
     required uint32 layer = 1;
 }