Introduce some util code for drawing vector assets.

ui/views/controls/throbber.cc

Index: ui/views/controls/throbber.cc
diff --git a/ui/views/controls/throbber.cc b/ui/views/controls/throbber.cc
index 9ecdbd7303236fe9870900ce12a67147ba30c205..f72659a000dae08b504314c406b50e5d5a9a2330 100644
--- a/ui/views/controls/throbber.cc
+++ b/ui/views/controls/throbber.cc
@@ -10,6 +10,7 @@
 #include "ui/gfx/image/image.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/paint_throbber.h"
+#include "ui/gfx/vector_icons.h"
 #include "ui/native_theme/common_theme.h"
 #include "ui/native_theme/native_theme.h"
 #include "ui/resources/grit/ui_resources.h"
@@ -17,7 +18,7 @@
 
 namespace views {
 
-Throbber::Throbber() : checked_(false), checkmark_(nullptr) {
+Throbber::Throbber() : checked_(false) {
 }
 
 Throbber::~Throbber() {
@@ -57,23 +58,20 @@ gfx::Size Throbber::GetPreferredSize() const {
 }
 
 void Throbber::OnPaint(gfx::Canvas* canvas) {
+  SkColor color = GetNativeTheme()->GetSystemColor(
+      ui::NativeTheme::kColorId_ThrobberSpinningColor);
+
   if (!IsRunning()) {
     if (checked_) {
-      if (!checkmark_) {
-        checkmark_ = ui::ResourceBundle::GetSharedInstance()
-                         .GetImageNamed(IDR_CHECKMARK)
-                         .ToImageSkia();
-      }
-
-      int checkmark_x = (width() - checkmark_->width()) / 2;
-      int checkmark_y = (height() - checkmark_->height()) / 2;
-      canvas->DrawImageInt(*checkmark_, checkmark_x, checkmark_y);
+      const int kDipSize = 18;

[Peter Kasting, 2015/07/01 22:26:58]

Hardcoding this makes me sad... is there any way to compute it from e.g. the
throbber's preferred size, or share this constant with other places, or
something?

[Evan Stade, 2015/07/02 00:08:06]

Yea, it's tricky. 18 is the magic dp for which the actual circle (less padding)
is 16dp. That is implicit in the drawing instructions, so not sure how to share.
I can move these constants to the same place and add a note to reduce the
probability of this breaking.

+      canvas->Translate(gfx::Vector2d((width() - kDipSize) / 2,
+                                      (height() - kDipSize) / 2));
+      gfx::PaintVectorIcon(canvas, gfx::VectorIconId::CHECK_CIRCLE, kDipSize,
+                           color);
     }
     return;
   }
 
-  SkColor color = GetNativeTheme()->GetSystemColor(
-      ui::NativeTheme::kColorId_ThrobberSpinningColor);
   base::TimeDelta elapsed_time = base::TimeTicks::Now() - start_time_;
   gfx::PaintThrobberSpinning(canvas, GetContentsBounds(), color, elapsed_time);
 }