Add unit tests for TabGridDialogMediator

Bug: 979410
Change-Id: I520c1ad7619c5852ce0df0160a4ed5439329602b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1681025
Commit-Queue: Yue Zhang <yuezhanggg@google.com>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#673446}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabGridDialogMediator.java

@@ -9,6 +9,7 @@ import android.graphics.Rect;
 import android.support.annotation.Nullable;
 import android.view.View;
 
+import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tabmodel.EmptyTabModelObserver;
 import org.chromium.chrome.browser.tabmodel.TabCreatorManager;
@@ -246,4 +247,14 @@ public class TabGridDialogMediator {
             updateDialog();
         }
     }
+
+    @VisibleForTesting
+    int getCurrentTabIdForTest() {
+        return mCurrentTabId;
+    }
+
+    @VisibleForTesting
+    void setCurrentTabIdForTest(int tabId) {
+        mCurrentTabId = tabId;
+    }
 }

chrome/android/features/tab_ui/tab_management_java_sources.gni

@@ -20,6 +20,7 @@ tab_management_test_java_sources = [
 
 tab_management_junit_java_sources = [
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/GridTabSwitcherMediatorUnitTest.java",
+  "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabGridDialogMediatorUnitTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabGridItemTouchHelperCallbackUnitTest.java",
   "//chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediatorUnitTest.java",
 ]