Improve panel tests by properly waiting for expected conditions.

chrome/browser/ui/panels/panel_drag_browsertest.cc

Index: chrome/browser/ui/panels/panel_drag_browsertest.cc
diff --git a/chrome/browser/ui/panels/panel_drag_browsertest.cc b/chrome/browser/ui/panels/panel_drag_browsertest.cc
index e87e87875bbe784d9fffda0d86d9b3ed76d86c9a..6bc24c5a07e51f5d1c7dbbe36d3577e1bb5470f3 100644
--- a/chrome/browser/ui/panels/panel_drag_browsertest.cc
+++ b/chrome/browser/ui/panels/panel_drag_browsertest.cc
@@ -10,6 +10,10 @@
 #include "chrome/browser/ui/panels/panel.h"
 #include "chrome/browser/ui/panels/panel_drag_controller.h"
 #include "chrome/browser/ui/panels/panel_manager.h"
+#include "chrome/browser/ui/panels/test_panel_strip_squeeze_observer.h"
+#include "chrome/common/chrome_notification_types.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/test/test_utils.h"
 
 class PanelDragBrowserTest : public BasePanelBrowserTest {
  public:
@@ -1221,6 +1225,10 @@ IN_PROC_BROWSER_TEST_F(PanelDragBrowserTest, AttachWithSqueeze) {
   ASSERT_EQ(3, detached_strip->num_panels());
   ASSERT_EQ(4, docked_strip->num_panels());
 
+  // Wait for active states to settle.
+  PanelStripSqueezeObserver panel7_settled(docked_strip, panel7);
+  panel7_settled.Wait();
+
   gfx::Point detached_position1 = panel1->GetBounds().origin();
   gfx::Point detached_position2 = panel2->GetBounds().origin();
   gfx::Point detached_position3 = panel3->GetBounds().origin();
@@ -1266,7 +1274,8 @@ IN_PROC_BROWSER_TEST_F(PanelDragBrowserTest, AttachWithSqueeze) {
 #else
   // The last panel is active so these positions do not change.
   // TODO (ABurago) this is wrong behavior, a panel should activate
-  // when it is dragged. Change the test when the behavior is fixed.
+  // when it is dragged (it does in real usage, but not when drag is
+  // simulated in a test). Change this test when the behavior is fixed.
   EXPECT_EQ(true, panel7->IsActive());
   EXPECT_EQ(panel7->GetBounds().width(), panel7->GetRestoredBounds().width());