Check for null MiniPlayerMediator in coordinator methods

Bug: 1474098
Change-Id: I6123617fd11f5a2d4513ba4a1b6cbe9b03d0f68f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4795433
Reviewed-by: Megan Jablonski <megjablon@chromium.org>
Commit-Queue: Megan Jablonski <megjablon@chromium.org>
Commit-Queue: Ian Wells <iwells@chromium.org>
Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
Auto-Submit: Ian Wells <iwells@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1185438}

chrome/browser/readaloud/android/java/src/org/chromium/chrome/browser/readaloud/miniplayer/MiniPlayerCoordinator.java

@@ -96,6 +96,9 @@ public void onCloseClicked() {
      * Returns the mini player visibility state.
      */
     public @PlayerState int getState() {
+        if (mMediator == null) {
+            return PlayerState.GONE;
+        }
         return mMediator.getState();
     }
 
@@ -105,6 +108,9 @@ public void onCloseClicked() {
      *         instantly disappear (though web contents resizing may lag behind).
      */
     public void dismiss(boolean animate) {
+        if (mMediator == null) {
+            return;
+        }
         mMediator.dismiss(animate);
     }
 }

chrome/browser/readaloud/android/java/src/org/chromium/chrome/browser/readaloud/miniplayer/MiniPlayerCoordinatorUnitTest.java

@@ -4,6 +4,7 @@
 
 package org.chromium.chrome.browser.readaloud.miniplayer;
 
+import static org.junit.Assert.assertEquals;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.eq;
 import static org.mockito.Mockito.never;
@@ -27,6 +28,7 @@
 import org.robolectric.annotation.Config;
 
 import org.chromium.base.test.BaseRobolectricTestRunner;
+import org.chromium.chrome.browser.readaloud.PlayerState;
 import org.chromium.chrome.browser.readaloud.R;
 import org.chromium.chrome.browser.readaloud.miniplayer.MiniPlayerCoordinator.Observer;
 
@@ -105,4 +107,18 @@ public void testObserveExpand() {
 
         verify(mObserver, times(1)).onExpandRequested();
     }
+
+    @Test
+    public void testDismissWhenNeverShown() {
+        // Check that methods depending on the mediator don't crash when it's null.
+        assertEquals(PlayerState.GONE, mCoordinator.getState());
+        mCoordinator.dismiss(false);
+    }
+
+    @Test
+    public void testShowDismiss() {
+        mCoordinator.show(/*animate=*/false, /*playback=*/null);
+        mCoordinator.dismiss(/*animate=*/false);
+        assertEquals(PlayerState.GONE, mCoordinator.getState());
+    }
 }