Clean up View Recycling

Summary:
Followups to View Recycling diffs to improve things / clean up things a bit. This also fixes memory warnings which were not hooked up before.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D36707792

fbshipit-source-id: 410e70bf0eeec5569566138af547e1601394d0e6

ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewManagerRegistry.java

@@ -19,11 +19,10 @@ import java.util.Map;
  * Class that stores the mapping between native view name used in JS and the corresponding instance
  * of {@link ViewManager}.
  */
-public final class ViewManagerRegistry {
+public final class ViewManagerRegistry implements ComponentCallbacks2 {
 
   private final Map<String, ViewManager> mViewManagers;
   private final @Nullable ViewManagerResolver mViewManagerResolver;
-  private final MemoryTrimCallback mMemoryTrimCallback = new MemoryTrimCallback();
 
   public ViewManagerRegistry(ViewManagerResolver viewManagerResolver) {
     mViewManagers = MapBuilder.newHashMap();
@@ -46,40 +45,6 @@ public final class ViewManagerRegistry {
     mViewManagerResolver = null;
   }
 
-  /**
-   * Trim View Recycling memory aggressively. Whenever the system is running even slightly low on
-   * memory or is backgrounded, we immediately flush all recyclable Views. GC and memory swaps cause
-   * intense CPU pressure, so we always favor low memory usage over View recycling, even if there is
-   * only "moderate" pressure.
-   */
-  private class MemoryTrimCallback implements ComponentCallbacks2 {
-    @Override
-    public void onTrimMemory(int level) {
-      Runnable runnable =
-          new Runnable() {
-            @Override
-            public void run() {
-              for (Map.Entry<String, ViewManager> entry : mViewManagers.entrySet()) {
-                entry.getValue().trimMemory();
-              }
-            }
-          };
-      if (UiThreadUtil.isOnUiThread()) {
-        runnable.run();
-      } else {
-        UiThreadUtil.runOnUiThread(runnable);
-      }
-    }
-
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {}
-
-    @Override
-    public void onLowMemory() {
-      this.onTrimMemory(0);
-    }
-  }
-
   /**
    * @param className {@link String} that identifies the {@link ViewManager} inside the {@link
    *     ViewManagerRegistry}. This methods {@throws IllegalViewOperationException} if there is no
@@ -147,4 +112,33 @@ public final class ViewManagerRegistry {
       UiThreadUtil.runOnUiThread(runnable);
     }
   }
+
+  /** ComponentCallbacks2 method. */
+  @Override
+  public void onTrimMemory(int level) {
+    Runnable runnable =
+        new Runnable() {
+          @Override
+          public void run() {
+            for (Map.Entry<String, ViewManager> entry : mViewManagers.entrySet()) {
+              entry.getValue().trimMemory();
+            }
+          }
+        };
+    if (UiThreadUtil.isOnUiThread()) {
+      runnable.run();
+    } else {
+      UiThreadUtil.runOnUiThread(runnable);
+    }
+  }
+
+  /** ComponentCallbacks2 method. */
+  @Override
+  public void onConfigurationChanged(Configuration newConfig) {}
+
+  /** ComponentCallbacks2 method. */
+  @Override
+  public void onLowMemory() {
+    this.onTrimMemory(0);
+  }
 }