polychrome: mark missed BrowserActionsContainerOverflowTest as Views-only

This test relies on having a BrowserView to get a ToolbarView. Since
ToolbarView is never used without BrowserView, only run this test in Views mode.

TBR=pkasting@chromium.org

Bug: 817408
Change-Id: I6f3388cf72356f8657f74637967d2e27c0db80d1
Reviewed-on: https://chromium-review.googlesource.com/975624Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#545072}

chrome/browser/ui/views/toolbar/browser_actions_container_browsertest.cc

@@ -277,6 +277,8 @@ class BrowserActionsContainerOverflowTest
   void SetUpOnMainThread() override;
   void TearDownOnMainThread() override;
 
+  test::ScopedMacViewsBrowserMode views_mode_{true};
+
   // The main BrowserActionsContainer (owned by the browser view).
   BrowserActionsContainer* main_bar_;
 
@@ -397,14 +399,8 @@ IN_PROC_BROWSER_TEST_F(BrowserActionsContainerOverflowTest,
   EXPECT_TRUE(VerifyVisibleCount(1u));
 }
 
-class BrowserActionsContainerOverflowViewsTest
-    : public BrowserActionsContainerOverflowTest {
- private:
-  test::ScopedMacViewsBrowserMode views_mode_{true};
-};
-
 // Test drag and drop between the overflow container and the main container.
-IN_PROC_BROWSER_TEST_F(BrowserActionsContainerOverflowViewsTest,
+IN_PROC_BROWSER_TEST_F(BrowserActionsContainerOverflowTest,
                        TestOverflowDragging) {
   LoadExtensions();