Don't animate a progress bar if it isn't animated

third_party/WebKit/Source/core/layout/LayoutProgress.cpp

Index: third_party/WebKit/Source/core/layout/LayoutProgress.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutProgress.cpp b/third_party/WebKit/Source/core/layout/LayoutProgress.cpp
index 5b2c45cf7b105c6d8d61788b09b3473ac276dcad..f9391543397bd5deefbc0cf123b33310d32ab546 100644
--- a/third_party/WebKit/Source/core/layout/LayoutProgress.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutProgress.cpp
@@ -74,6 +74,11 @@ bool LayoutProgress::isDeterminate() const
         && HTMLProgressElement::InvalidPosition != position());
 }
 
+bool LayoutProgress::isAnimationTimerActive() const
+{
+    return m_animationTimer.isActive();

[Xianzhu, 2016/02/22 23:17:27]

Nit: Can you use m_animating (and rename this function to isAnimating())?

[Stephen Chennney, 2016/02/23 19:24:01]

I would rather check the timer itself, as that will catch bugs with both
m_animating being set and the timer being set (because the timer can only be
right is m_animating is right).

Better yet is to check both the flag and the timer, which will test that the
code keeps them correctly in sync.

+}
+
 void LayoutProgress::animationTimerFired(Timer<LayoutProgress>*)
 {
     setShouldDoFullPaintInvalidation();
@@ -86,7 +91,7 @@ void LayoutProgress::updateAnimationState()
     m_animationDuration = LayoutTheme::theme().animationDurationForProgressBar();
     m_animationRepeatInterval = LayoutTheme::theme().animationRepeatIntervalForProgressBar();
 
-    bool animating = style()->hasAppearance() && m_animationDuration > 0;
+    bool animating = !isDeterminate() && style()->hasAppearance() && m_animationDuration > 0;
     if (animating == m_animating)
         return;