Override onTrimMemory to apply trimMemory in AppIconCacheManager

This CL adapts new trimMemory mechanism when device running moderately
low on memory.

Bug: 259630755
Test: manual
Change-Id: I6501b834ce3327f47e911600ac6fe2f09a80e54e

src/com/android/settings/SettingsApplication.java

@@ -47,8 +47,8 @@ public class SettingsApplication extends Application {
     }
 
     @Override
-    public void onLowMemory() {
-        super.onLowMemory();
-        AppIconCacheManager.getInstance().release();
+    public void onTrimMemory(int level) {
+        super.onTrimMemory(level);
+        AppIconCacheManager.getInstance().trimMemory(level);
     }
 }