Mac: Added a delay before panels go to minimized state from title-only state.

chrome/browser/ui/panels/panel_manager.cc

Index: chrome/browser/ui/panels/panel_manager.cc
diff --git a/chrome/browser/ui/panels/panel_manager.cc b/chrome/browser/ui/panels/panel_manager.cc
index 5bb2bc8d0dc8b9280c3408159ef4e5e4dda75585..eaa2b0432b9887ab4c937e68f9bcdddc7d00a94c 100644
--- a/chrome/browser/ui/panels/panel_manager.cc
+++ b/chrome/browser/ui/panels/panel_manager.cc
@@ -32,11 +32,21 @@ const double kPanelMaxHeightFactor = 0.5;
 // After the time expires, we bring up/down the titlebars as planned.
 const int kMaxMillisecondsWaitForBottomBarVisibilityChange = 1000;
 
+// See usage below.
+#if defined(OS_MACOSX)
+const int kMillisecondsBeforeCollapsingFromTitleonlyState = 3000;
+#else
+const int kMillisecondsBeforeCollapsingFromTitleonlyState = 0;
+#endif
+
 // Single instance of PanelManager.
 scoped_refptr<PanelManager> panel_manager_instance;
 }  // namespace
 
 // static
+int PanelManager::s_last_task_index = 0;
+
+// static
 PanelManager* PanelManager::GetInstance() {
   if (!panel_manager_instance.get())
     panel_manager_instance = new PanelManager();
@@ -49,6 +59,7 @@ PanelManager::PanelManager()
       dragging_panel_index_(kInvalidPanelIndex),
       dragging_panel_original_x_(0),
       delayed_titlebar_action_(NO_ACTION),
+      reduced_delays_for_testing_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(method_factory_(this)),
       auto_sizing_enabled_(true),
       mouse_watching_disabled_(false) {
@@ -392,6 +403,7 @@ bool PanelManager::ShouldBringUpTitlebars(int mouse_x, int mouse_y) const {
 }
 
 void PanelManager::BringUpOrDownTitlebars(bool bring_up) {
+  int task_delay = 0;

[jianli, 2011/10/28 21:31:33]

Please add an empty line here.
Also, task_delay_time?

[Dmitry Titov, 2011/10/29 00:04:56]

made it task_delay_milliseconds.

   // If the auto-hiding bottom bar exists, delay the action until the bottom
   // bar is fully visible or hidden. We do not want both bottom bar and panel
   // titlebar to move at the same time but with different speeds.
@@ -400,33 +412,60 @@ void PanelManager::BringUpOrDownTitlebars(bool bring_up) {
         GetVisibility(AutoHidingDesktopBar::ALIGN_BOTTOM);
     if (visibility != (bring_up ? AutoHidingDesktopBar::VISIBLE
                                 : AutoHidingDesktopBar::HIDDEN)) {
-      // OnAutoHidingDesktopBarVisibilityChanged will handle this.
-      delayed_titlebar_action_ = bring_up ? BRING_UP : BRING_DOWN;
-
       // Occasionally some system, like Windows, might not bring up or down the
       // bottom bar when the mouse enters or leaves the bottom screen area.
       // Thus, we schedule a delayed task to do the work if we do not receive
       // the bottom bar visibility change notification within a certain period
       // of time.
-      MessageLoop::current()->PostDelayedTask(
-          FROM_HERE,
-          method_factory_.NewRunnableMethod(
-              &PanelManager::DelayedBringUpOrDownTitlebarsCheck),
-          kMaxMillisecondsWaitForBottomBarVisibilityChange);
-
-      return;
+      task_delay = kMaxMillisecondsWaitForBottomBarVisibilityChange;
     }
   }
 
-  DoBringUpOrDownTitlebars(bring_up);
+  // On some OSes, the interaction with native Taskbars/Docks may be improved
+  // if the panels do not go back to minimized state too fast. For example,
+  // it makes it possible to hit the titlebar on OSX if Dock has Magnifying
+  // enabled - the panels stay up for a while after Dock magnification effect
+  // stops covering the panels.
+  if (!bring_up) {
+    if (task_delay < kMillisecondsBeforeCollapsingFromTitleonlyState)
+      task_delay = kMillisecondsBeforeCollapsingFromTitleonlyState;
+  }
+
+  // OnAutoHidingDesktopBarVisibilityChanged will handle this.
+  delayed_titlebar_action_ = bring_up ? BRING_UP : BRING_DOWN;
+  if (reduced_delays_for_testing_)

[jianli, 2011/10/28 21:31:33]

This sounds more like removed_delays_for_testing_

[Dmitry Titov, 2011/10/29 00:04:56]

renamed to remove_delays_for_testing_

+    task_delay = 0;
+
+  MessageLoop::current()->PostDelayedTask(
+      FROM_HERE,
+      method_factory_.NewRunnableMethod(
+          &PanelManager::DelayedBringUpOrDownTitlebarsCheck,
+          ++s_last_task_index),

[jianli, 2011/10/28 21:31:33]

I think we can avoid using this static variable in the following way:
  if (!delayed_titlebars_action_task_posted_) {
    MessageLoop::current()->PostDelayedTask(...);
    delayed_titlebars_action_task_posted_ = true;
  }
  

[Dmitry Titov, 2011/10/29 00:04:56]

Replaced by using Cancel() on a task. Keep the pointer to the task now.

+      task_delay);
 }
 
-void PanelManager::DelayedBringUpOrDownTitlebarsCheck() {
+void PanelManager::DelayedBringUpOrDownTitlebarsCheck(int task_index) {
+  // Task was already processed or cancelled - bail out.
   if (delayed_titlebar_action_ == NO_ACTION)
     return;
 
-  DoBringUpOrDownTitlebars(delayed_titlebar_action_ == BRING_UP);
+  // In case we posted multiple tasks because user was moving mouse back and
+  // forth, ignore all but the last one.
+  if (task_index < s_last_task_index)
+    return;
+  DCHECK(task_index == s_last_task_index);
+
+  bool need_to_bring_titlebars_up = (delayed_titlebar_action_ == BRING_UP);

[jianli, 2011/10/28 21:31:33]

need_to_bring_titlebars_up => need_to_bring_up_titlebars

[Dmitry Titov, 2011/10/29 00:04:56]

Done

+
+  // We are going to process the task one way or another after this point.

[jianli, 2011/10/28 21:31:33]

This comment is kind of confusing. Why not removing it?

[Dmitry Titov, 2011/10/29 00:04:56]

Done.

   delayed_titlebar_action_ = NO_ACTION;
+
+  // Check if the action is still needed based on mouse position. In case the
+  // mouse moved and does not call for the titlebars change, cancel.

[jianli, 2011/10/28 21:31:33]

Comment here is a bit hard to understand. How about rephrasing like:
  // Check if the action is still needed based on the latest mouse position. The
user could move the mouse into the tracking area and then quickly move it out of
the area. In case of this, cancel the action.

[Dmitry Titov, 2011/10/29 00:04:56]

Done.

+  if (are_titlebars_up_ != need_to_bring_titlebars_up)
+    return;
+
+  DoBringUpOrDownTitlebars(need_to_bring_titlebars_up);
 }
 
 void PanelManager::DoBringUpOrDownTitlebars(bool bring_up) {