feedv2: populate feed after clear

Bug: 1111806
Change-Id: I7662de6b7117a5434417a7b430b54bc042817175
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2333995Reviewed-by: Cathy Li <chili@chromium.org>
Commit-Queue: Dan H <harringtond@chromium.org>
Cr-Commit-Position: refs/heads/master@{#795033}

chrome/android/feed/core/java/src/org/chromium/chrome/browser/feed/v2/FeedStreamSurface.java

@@ -168,8 +168,10 @@ public class FeedStreamSurface implements SurfaceActionsHandler, FeedActionsHand
      *  Clear all the data related to all surfaces.
      */
     public static void clearAll() {
+        FeedStreamSurface[] surfaces = null;
         if (sSurfaces != null) {
-            for (FeedStreamSurface surface : sSurfaces) {
+            surfaces = sSurfaces.toArray(new FeedStreamSurface[sSurfaces.size()]);
+            for (FeedStreamSurface surface : surfaces) {
                 surface.surfaceClosed();
             }
             sSurfaces = null;
@@ -179,6 +181,12 @@ public class FeedStreamSurface implements SurfaceActionsHandler, FeedActionsHand
         if (processScope != null) {
             processScope.resetAccount();
         }
+
+        if (surfaces != null) {
+            for (FeedStreamSurface surface : surfaces) {
+                surface.surfaceOpened();
+            }
+        }
     }
 
     /**

chrome/android/junit/src/org/chromium/chrome/browser/feed/v2/FeedStreamSurfaceTest.java

@@ -38,6 +38,7 @@ import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
 import org.mockito.ArgumentMatchers;
 import org.mockito.Captor;
+import org.mockito.InOrder;
 import org.mockito.Mock;
 import org.mockito.Mockito;
 import org.mockito.MockitoAnnotations;
@@ -590,12 +591,17 @@ public class FeedStreamSurfaceTest {
     @SmallTest
     public void testClearAll() {
         FeedStreamSurface.startup();
+        InOrder order = Mockito.inOrder(mFeedStreamSurfaceJniMock, mProcessScope);
         mFeedStreamSurface.surfaceOpened();
-        verify(mFeedStreamSurfaceJniMock).surfaceOpened(anyLong(), any(FeedStreamSurface.class));
+        order.verify(mFeedStreamSurfaceJniMock)
+                .surfaceOpened(anyLong(), any(FeedStreamSurface.class));
 
         FeedStreamSurface.clearAll();
-        verify(mFeedStreamSurfaceJniMock).surfaceClosed(anyLong(), any(FeedStreamSurface.class));
-        verify(mProcessScope).resetAccount();
+        order.verify(mFeedStreamSurfaceJniMock)
+                .surfaceClosed(anyLong(), any(FeedStreamSurface.class));
+        order.verify(mProcessScope).resetAccount();
+        order.verify(mFeedStreamSurfaceJniMock)
+                .surfaceOpened(anyLong(), any(FeedStreamSurface.class));
     }
 
     @Test