Switch the default blur algorithm to Kawase2.

Bug: 353826438
Test: m -j. Visually inspect blur effect.
Flag: com.android.graphics.surfaceflinger.flags.window_blur_kawase2
Change-Id: I7f9a02e16058ab9393bd8bbc925f344494450a39
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 59b1917..bab59d1 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -877,6 +877,9 @@
     } else if (algorithm == "kawase2") {
         return renderengine::RenderEngine::BlurAlgorithm::KAWASE_DUAL_FILTER;
     } else {
+        if (FlagManager::getInstance().window_blur_kawase2()) {
+            return renderengine::RenderEngine::BlurAlgorithm::KAWASE_DUAL_FILTER;
+        }
         return renderengine::RenderEngine::BlurAlgorithm::KAWASE;
     }
 }