Align the loading animation to pixel bounds

This is done by disabling anti aliasing. As we're painting a single
solid rectangle this is equivalent (and probably marginally faster).

Bug: chromium:907641
Change-Id: I05dec569b963511ce87f0a24d0f2f443fa0d9889
Reviewed-on: https://chromium-review.googlesource.com/c/1352338Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Peter Boström <pbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611380}

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

@@ -339,7 +339,8 @@ void TabIcon::PaintLoadingProgressIndicator(gfx::Canvas* canvas,
   cc::PaintFlags flags;
   flags.setColor(color);
   flags.setStyle(cc::PaintFlags::kFill_Style);
-  flags.setAntiAlias(true);
+  // Disable anti-aliasing to effectively "pixel align" the rectangle.
+  flags.setAntiAlias(false);
   flags.setAlpha(animation_state_.loading_progress_alpha);
 
   canvas->DrawRect(bounds, flags);

ui/gfx/paint_throbber.cc

@@ -222,7 +222,8 @@ GFX_EXPORT void PaintNewThrobberWaiting(Canvas* canvas,
   cc::PaintFlags flags;
   flags.setColor(color);
   flags.setStyle(cc::PaintFlags::kFill_Style);
-  flags.setAntiAlias(true);
+  // Disable anti-aliasing to effectively "pixel align" the rectangle.
+  flags.setAntiAlias(false);
 
   // Draw with circular end caps.
   canvas->DrawRect(bounds, flags);