Remove unnecessary spin in ToolTipController

ui/views/corewm/tooltip_controller.cc

Index: ui/views/corewm/tooltip_controller.cc
diff --git a/ui/views/corewm/tooltip_controller.cc b/ui/views/corewm/tooltip_controller.cc
index cd1792ffa29d03692804fa4162d8a450adcb171c..c2d8462b61a81ab1ccf662cdf4485a141c67f35c 100644
--- a/ui/views/corewm/tooltip_controller.cc
+++ b/ui/views/corewm/tooltip_controller.cc
@@ -30,7 +30,6 @@ namespace views {
 namespace corewm {
 namespace {
 
-const int kTooltipTimeoutMs = 500;
 const int kDefaultTooltipShownTimeoutMs = 10000;
 #if defined(OS_WIN)
 // Drawing a long word in tooltip is very slow on Windows. crbug.com/513693
@@ -129,11 +128,7 @@ TooltipController::TooltipController(std::unique_ptr<Tooltip> tooltip)
       tooltip_id_(NULL),
       tooltip_window_at_mouse_press_(NULL),
       tooltip_(std::move(tooltip)),
-      tooltips_enabled_(true) {
-  tooltip_timer_.Start(FROM_HERE,
-      base::TimeDelta::FromMilliseconds(kTooltipTimeoutMs),
-      this, &TooltipController::TooltipTimerFired);
-}
+      tooltips_enabled_(true) {}
 
 TooltipController::~TooltipController() {
   if (tooltip_window_)
@@ -160,17 +155,6 @@ void TooltipController::UpdateTooltip(aura::Window* target) {
       aura::client::GetTooltipText(target) != tooltip_text_at_mouse_press_) {
     tooltip_window_at_mouse_press_ = NULL;
   }
-
-  // If we had stopped the tooltip timer for some reason, we must restart it if
-  // there is a change in the tooltip.
-  if (!tooltip_timer_.IsRunning()) {
-    if (tooltip_window_ != target || (tooltip_window_ &&
-        tooltip_text_ != aura::client::GetTooltipText(tooltip_window_))) {
-      tooltip_timer_.Start(FROM_HERE,
-          base::TimeDelta::FromMilliseconds(kTooltipTimeoutMs),
-          this, &TooltipController::TooltipTimerFired);
-    }
-  }
 }
 
 void TooltipController::SetTooltipShownTimeout(aura::Window* target,
@@ -211,10 +195,10 @@ void TooltipController::OnMouseEvent(ui::MouseEvent* event) {
         target = GetTooltipTarget(*event, &curr_mouse_loc_);
       }
       SetTooltipWindow(target);
-      if (tooltip_timer_.IsRunning())
-        tooltip_timer_.Reset();
 
-      if (tooltip_->IsVisible())
+      if (tooltip_->IsVisible() || tooltip_window_ != target ||
+          (tooltip_window_ &&
+           tooltip_text_ != aura::client::GetTooltipText(tooltip_window_)))

[brucedawson, 2017/01/06 20:45:23]

I don't understand why this logic has changed. Can you explain?

I don't know the code well so maybe it is obvious to somebody who does know it.

[chengx, 2017/01/06 20:58:19]

Previously, mouse event handlers update tooltip only when tooltip is visible.
Therefore, if we remove the repeating timer, tooltip won't be updated to visible
state no matter what. I changed the logic here so that when mouse is moved to
hover on a window where there is tooltip, the tooltip will become visible.

         UpdateIfRequired();
       break;
     }
@@ -232,10 +216,6 @@ void TooltipController::OnMouseEvent(ui::MouseEvent* event) {
       // Hide the tooltip for click, release, drag, wheel events.
       if (tooltip_->IsVisible())
         tooltip_->Hide();
-
-      // Don't reshow the tooltip during scroll.
-      if (tooltip_timer_.IsRunning())
-        tooltip_timer_.Reset();
       break;
     default:
       break;
@@ -266,17 +246,8 @@ void TooltipController::OnWindowDestroyed(aura::Window* window) {
 ////////////////////////////////////////////////////////////////////////////////
 // TooltipController private:
 
-void TooltipController::TooltipTimerFired() {
-  UpdateIfRequired();
-}
-
 void TooltipController::TooltipShownTimerFired() {
   tooltip_->Hide();
-
-  // Since the user presumably no longer needs the tooltip, we also stop the
-  // tooltip timer so that tooltip does not pop back up. We will restart this
-  // timer if the tooltip changes (see UpdateTooltip()).
-  tooltip_timer_.Stop();
 }
 
 void TooltipController::UpdateIfRequired() {