Avoid unnecessary visibility changes to BookmarkBarView

chrome/browser/ui/views/frame/browser_view_browsertest.cc

Index: chrome/browser/ui/views/frame/browser_view_browsertest.cc
diff --git a/chrome/browser/ui/views/frame/browser_view_browsertest.cc b/chrome/browser/ui/views/frame/browser_view_browsertest.cc
index d10c90c9797a759d946b945cf1ab9068e94f7630..25dced611bfe23f40ed34efe9e050d5e121502ce 100644
--- a/chrome/browser/ui/views/frame/browser_view_browsertest.cc
+++ b/chrome/browser/ui/views/frame/browser_view_browsertest.cc
@@ -4,11 +4,17 @@
 
 #include "chrome/browser/ui/views/frame/browser_view.h"
 
+#include "base/prefs/pref_service.h"
 #include "chrome/browser/devtools/devtools_window_testing.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/browser/ui/views/bookmarks/bookmark_bar_view.h"
+#include "chrome/browser/ui/views/bookmarks/bookmark_bar_view_observer.h"
+#include "chrome/common/url_constants.h"
 #include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/ui_test_utils.h"
+#include "components/bookmarks/common/bookmark_pref_names.h"
 #include "content/public/browser/invalidate_type.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/browser/web_contents_observer.h"
@@ -166,3 +172,70 @@ IN_PROC_BROWSER_TEST_F(BrowserViewTest, DevToolsUpdatesBrowserWindow) {
   EXPECT_EQ(full_bounds, devtools_web_view()->bounds());
   EXPECT_EQ(full_bounds, contents_web_view()->bounds());
 }
+
+class BookmarkBarViewObserverImpl : public BookmarkBarViewObserver {
+ public:
+  BookmarkBarViewObserverImpl() : change_count_(0) {
+  }
+
+  int change_count() const { return change_count_; }
+  void clear_change_count() { change_count_ = 0; }
+
+  // BookmarkBarViewObserver:
+  virtual void OnBookmarkBarVisibilityChanged() OVERRIDE {
+    change_count_++;
+  }
+
+ private:
+  int change_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(BookmarkBarViewObserverImpl);
+};
+
+// Verifies we don't unnecessarily change the visibility of the BookmarkBarView.
+IN_PROC_BROWSER_TEST_F(BrowserViewTest, AvoidUnnecessaryVisibilityChanges) {
+  // Create two tabs, the first empty and the second the ntp. Make it so the
+  // BookmarkBarView isn't shown (meaning it'll only be shown when on the ntp).
+  browser()->profile()->GetPrefs()->SetBoolean(
+      bookmarks::prefs::kShowBookmarkBar, false);
+  GURL new_tab_url(chrome::kChromeUINewTabURL);
+  chrome::AddTabAt(browser(), GURL(), -1, true);
+  ui_test_utils::NavigateToURL(browser(), new_tab_url);
+
+  ASSERT_TRUE(browser_view()->bookmark_bar());
+  BookmarkBarViewObserverImpl observer;
+  BookmarkBarView* bookmark_bar = browser_view()->bookmark_bar();
+  bookmark_bar->AddObserver(&observer);
+  EXPECT_TRUE(bookmark_bar->visible());
+
+  // Go to empty tab. Bookmark bar should hide.
+  browser()->tab_strip_model()->ActivateTabAt(0, true);
+  EXPECT_FALSE(bookmark_bar->visible());
+  EXPECT_EQ(1, observer.change_count());
+  observer.clear_change_count();
+
+  // Go to ntp tab. Bookmark bar should show.
+  browser()->tab_strip_model()->ActivateTabAt(1, true);
+  EXPECT_TRUE(bookmark_bar->visible());
+  EXPECT_EQ(1, observer.change_count());
+  observer.clear_change_count();
+
+  // Repeat with the bookmark bar always visible.
+  browser()->profile()->GetPrefs()->SetBoolean(
+      bookmarks::prefs::kShowBookmarkBar, true);
+  browser()->tab_strip_model()->ActivateTabAt(1, true);
+  EXPECT_TRUE(bookmark_bar->visible());
+  observer.clear_change_count();
+
+  browser()->tab_strip_model()->ActivateTabAt(0, true);
+  EXPECT_TRUE(bookmark_bar->visible());
+  EXPECT_EQ(0, observer.change_count());
+  observer.clear_change_count();
+
+  browser()->tab_strip_model()->ActivateTabAt(1, true);
+  EXPECT_TRUE(bookmark_bar->visible());
+  EXPECT_EQ(0, observer.change_count());
+  observer.clear_change_count();
+
+  browser_view()->bookmark_bar()->RemoveObserver(&observer);
+}