[Jank] Add experiment to optimize SwipeRefreshHandler.

Currently the SwipeRefreshHandler sets z-order while pulling and
animating. However, this causes a re-layout of the UI. Moreover, when
completing the pull-refresh gesture, it ends up enqueing 5x layouts
while animating away and removing control. Add an experiment flag to
measure impact of doing a single re-layout at the start.

Bug: 1335416
Change-Id: I191a64e23dbdc0ed855cbb89d20b97ca0339006c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3703643
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Yaron Friedman <yfriedman@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1014996}

chrome/android/java/src/org/chromium/chrome/browser/SwipeRefreshHandler.java

@@ -17,6 +17,7 @@
 import org.chromium.base.metrics.RecordUserAction;
 import org.chromium.base.task.PostTask;
 import org.chromium.chrome.R;
+import org.chromium.chrome.browser.flags.ChromeFeatureList;
 import org.chromium.chrome.browser.gesturenav.HistoryNavigationCoordinator;
 import org.chromium.chrome.browser.tab.EmptyTabObserver;
 import org.chromium.chrome.browser.tab.Tab;
@@ -195,7 +196,8 @@ public boolean start(
         if (type == OverscrollAction.PULL_TO_REFRESH) {
             if (mSwipeRefreshLayout == null) initSwipeRefreshLayout(mTab.getContext());
             attachSwipeRefreshLayoutIfNecessary();
-            return mSwipeRefreshLayout.start();
+            return mSwipeRefreshLayout.start(ChromeFeatureList.isEnabled(
+                    ChromeFeatureList.OPTIMIZE_LAYOUTS_FOR_PULL_REFRESH));
         } else if (type == OverscrollAction.HISTORY_NAVIGATION) {
             if (mNavigationCoordinator != null) {
                 mNavigationCoordinator.startGesture();

chrome/browser/feed/android/java/src/org/chromium/chrome/browser/feed/FeedSwipeRefreshLayout.java

@@ -258,7 +258,8 @@ public boolean onInterceptTouchEvent(MotionEvent event) {
                 final float yDiff = y - mLastMotionY;
                 if (yDiff > mTouchSlop && !mIsBeingDragged) {
                     mIsBeingDragged = true;
-                    start();
+                    // TODO(1335416): Update this to |true| if experiment is successful
+                    start(false);
                 }
                 break;
             }

chrome/browser/flags/android/chrome_feature_list.cc

@@ -250,6 +250,7 @@ const base::Feature* const kFeaturesExposedToJava[] = {
     &kBookmarksImprovedSaveFlow,
     &kBookmarksRefresh,
     &kBackGestureRefactorAndroid,
+    &kOptimizeLayoutsForPullRefresh,
     &kPostTaskFocusTab,
     &kProbabilisticCryptidRenderer,
     &kReachedCodeProfiler,
@@ -714,6 +715,9 @@ const base::Feature kBookmarksRefresh{"BookmarksRefresh",
 const base::Feature kBackGestureRefactorAndroid{
     "BackGestureRefactorAndroid", base::FEATURE_DISABLED_BY_DEFAULT};
 
+const base::Feature kOptimizeLayoutsForPullRefresh{
+    "OptimizeLayoutsForPullRefresh", base::FEATURE_DISABLED_BY_DEFAULT};
+
 const base::Feature kPostTaskFocusTab{"PostTaskFocusTab",
                                       base::FEATURE_DISABLED_BY_DEFAULT};
 

chrome/browser/flags/android/chrome_feature_list.h

@@ -114,6 +114,7 @@ extern const base::Feature kPageAnnotationsService;
 extern const base::Feature kBookmarksImprovedSaveFlow;
 extern const base::Feature kBookmarksRefresh;
 extern const base::Feature kBackGestureRefactorAndroid;
+extern const base::Feature kOptimizeLayoutsForPullRefresh;
 extern const base::Feature kPostTaskFocusTab;
 extern const base::Feature kProbabilisticCryptidRenderer;
 extern const base::Feature kReachedCodeProfiler;

chrome/browser/flags/android/java/src/org/chromium/chrome/browser/flags/ChromeFeatureList.java

@@ -430,6 +430,7 @@ public static boolean getFieldTrialParamByFeatureAsBoolean(
             "OmniboxUpdatedConnectionSecurityIndicators";
     public static final String OPTIMIZATION_GUIDE_PUSH_NOTIFICATIONS =
             "OptimizationGuidePushNotifications";
+    public static final String OPTIMIZE_LAYOUTS_FOR_PULL_REFRESH = "OptimizeLayoutsForPullRefresh";
     public static final String OVERLAY_NEW_LAYOUT = "OverlayNewLayout";
     public static final String PAGE_ANNOTATIONS_SERVICE = "PageAnnotationsService";
     public static final String PAGE_INFO_ABOUT_THIS_SITE_EN = "PageInfoAboutThisSiteEn";

components/paint_preview/player/android/BUILD.gn

@@ -92,6 +92,7 @@ android_library("java") {
     "//base:base_java",
     "//base:jni_java",
     "//build/android:build_java",
+    "//chrome/browser/flags:java",
     "//components/browser_ui/styles/android:java",
     "//components/paint_preview/browser/android:java",
     "//content/public/android:content_java",

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/PlayerSwipeRefreshHandler.java

@@ -67,7 +67,8 @@ public View getView() {
 
     @Override
     public boolean start() {
-        return mSwipeRefreshLayout.start();
+        // TODO(1335416): Update this to |true| if experiment is successful
+        return mSwipeRefreshLayout.start(false);
     }
 
     @Override

third_party/android_swipe_refresh/README.chromium

@@ -28,3 +28,5 @@ SwipeRefreshLayout
   * All ViewCompat and MotionEventCompat dependencies removed.
   * Added OnResetListener interface to notify SwipeRefreshHandler to detach
     this view.
+  * Add a flag to minimze the number of z-order changes, thereby minimizing
+    relayouts of the UI.

third_party/android_swipe_refresh/java/src/org/chromium/third_party/android/swiperefresh/SwipeRefreshLayout.java

@@ -136,6 +136,12 @@ public class SwipeRefreshLayout extends ViewGroup {
 
     private boolean mNotify;
 
+    /**
+     * Flag used during duration of pull-refresh animation to reduce the number of calls to
+     * |bringToFront|, and therefore requested layouts. crbug/1335416
+     */
+    private boolean mOptimizeLayouts;
+
     private int mCircleWidth;
 
     private int mCircleHeight;
@@ -564,10 +570,11 @@ public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
      * is currently active, the request will be ignored.
      * @return whether a new pull sequence has started.
      */
-    public boolean start() {
+    public boolean start(boolean optimizeLayouts) {
         if (!isEnabled()) return false;
         if (mRefreshing) return false;
         mCircleView.clearAnimation();
+        mOptimizeLayouts = optimizeLayouts;
         mProgress.stop();
         // See ACTION_DOWN handling in {@link #onTouchEvent(...)}.
         setTargetOffsetTopAndBottom(mOriginalOffsetTop - mCircleView.getTop(), true);
@@ -636,6 +643,12 @@ public void pull(float delta) {
                 true /* requires update */);
     }
 
+    @Override
+    public void bringChildToFront(View child) {
+        if (mOptimizeLayouts && indexOfChild(child) == getChildCount() - 1) return;
+        super.bringChildToFront(child);
+    }
+
     /**
      * Release the active pull. If no pull has started, the release will be
      * ignored. If the pull was sufficiently large, the refresh sequence will