Update the tab-animation throbber style

Removes the round-rect end caps in favor of a rectangular throbber.

The throbber size and timings are also updated. See chromium:907435.

Bug: chromium:907422, chromium:907435
Change-Id: I7d7a18a4d19b18361db84de829a93475a57efa44
Reviewed-on: https://chromium-review.googlesource.com/c/1346091Reviewed-by: Edward Jung <edwardjung@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610083}

chrome/browser/ui/views/tabs/tab_icon.cc

@@ -276,7 +276,7 @@ void TabIcon::PaintLoadingProgressIndicator(gfx::Canvas* canvas,
                               (kProgressIndicatorAnimationDuration - 1.0)));
   }
 
-  canvas->DrawRoundRect(bounds, bounds.height() / 2, flags);
+  canvas->DrawRect(bounds, flags);
 }
 
 void TabIcon::PaintLoadingAnimation(gfx::Canvas* canvas,

ui/gfx/paint_throbber.cc

@@ -193,10 +193,16 @@ GFX_EXPORT void PaintNewThrobberWaiting(Canvas* canvas,
   float time = 2.0f * (elapsed_time.InMilliseconds() % kAnimationCycleMs) /
                kAnimationCycleMs;
   // 1 -> 2 values mirror back to 1 -> 0 values to represent right-to-left.
-  if (time > 1.0f)
+  const bool going_back = time > 1.0f;
+  if (going_back)
     time = 2.0f - time;
+  // This animation should be fast in the middle and slow at the edges.
+  time = Tween::CalculateValue(Tween::EASE_IN_OUT, time);
   const float min_width = throbber_container_bounds.height();
-  const float throbber_width = min_width * 2.5;
+  // The throbber animation stretches longer when moving in (left to right) than
+  // when going back.
+  const float throbber_width =
+      (going_back ? 0.75f : 1.0f) * throbber_container_bounds.width();
 
   // These bounds keep at least |min_width| of the throbber visible (inside the
   // throbber bounds).
@@ -219,7 +225,7 @@ GFX_EXPORT void PaintNewThrobberWaiting(Canvas* canvas,
   flags.setAntiAlias(true);
 
   // Draw with circular end caps.
-  canvas->DrawRoundRect(bounds, bounds.height() / 2, flags);
+  canvas->DrawRect(bounds, flags);
 }
 
 }  // namespace gfx