[Paint Preview] Match scroll position on exit

This CL matches the scroll position of the live tab to that of the
player on exiting paint preview.

Bug: 1121654
Change-Id: I8f36d827979418d5480811ffa367b22bf24fce19
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2375930Reviewed-by: Calder Kitagawa <ckitagawa@chromium.org>
Commit-Queue: Mehran Mahmoudi <mahmoudi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801530}

chrome/browser/paint_preview/android/java/src/org/chromium/chrome/browser/paint_preview/TabbedPaintPreviewPlayer.java

@@ -5,6 +5,7 @@
 package org.chromium.chrome.browser.paint_preview;
 
 import android.content.res.Resources;
+import android.graphics.Point;
 import android.os.Handler;
 import android.os.SystemClock;
 import android.view.View;
@@ -181,6 +182,11 @@ public class TabbedPaintPreviewPlayer implements TabViewProvider, UserData {
         mInitializing = false;
         if (mTab == null || mPlayerManager == null) return;
 
+        Point scrollPosition = mPlayerManager.getScrollPosition();
+        if (mTab.getWebContents() != null && scrollPosition != null) {
+            mTab.getWebContents().getEventForwarder().scrollTo(scrollPosition.x, scrollPosition.y);
+        }
+
         mTab.getTabViewManager().removeTabViewProvider(this);
         mPlayerManager.destroy();
         mPlayerManager = null;

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

@@ -5,6 +5,7 @@
 package org.chromium.components.paintpreview.player;
 
 import android.content.Context;
+import android.graphics.Point;
 import android.graphics.Rect;
 import android.view.View;
 import android.view.ViewGroup;
@@ -90,6 +91,16 @@ public class PlayerManager {
         mPlayerGestureListener.setUserFrustrationDetector(userFrustrationDetector);
     }
 
+    /**
+     * @return Current scroll position of the main frame. null if the player is not
+     * initialized.
+     */
+    public Point getScrollPosition() {
+        if (mRootFrameCoordinator == null) return null;
+
+        return mRootFrameCoordinator.getScrollPosition();
+    }
+
     /**
      * Called by {@link PlayerCompositorDelegateImpl} when the compositor is initialized. This
      * method initializes a sub-component for each frame and adds the view for the root frame to

components/paint_preview/player/android/java/src/org/chromium/components/paintpreview/player/frame/PlayerFrameCoordinator.java

@@ -5,6 +5,7 @@
 package org.chromium.components.paintpreview.player.frame;
 
 import android.content.Context;
+import android.graphics.Point;
 import android.graphics.Rect;
 import android.util.Size;
 import android.view.View;
@@ -63,6 +64,14 @@ public class PlayerFrameCoordinator {
         PropertyModelChangeProcessor.create(model, mView, PlayerFrameViewBinder::bind);
     }
 
+    public Point getScrollPosition() {
+        Rect viewPortRect = mMediator.getViewport().asRect();
+        float scaleFactor = mMediator.getViewport().getScale();
+        if (scaleFactor == 0) scaleFactor = 1;
+        return new Point(
+                (int) (viewPortRect.left / scaleFactor), (int) (viewPortRect.top / scaleFactor));
+    }
+
     /**
      * Adds a child {@link PlayerFrameCoordinator} to this class.
      * @param subFrame The sub-frame's {@link PlayerFrameCoordinator}.
@@ -76,7 +85,7 @@ public class PlayerFrameCoordinator {
     /**
      * @return The mediator associated with this component.
      */
-    public PlayerFrameMediator getMediator() {
+    private PlayerFrameMediator getMediator() {
         return mMediator;
     }