Added a nested class to gfx::Animation

The new class is a reimplementation of SlideAnimation::TestApi which
allows tests to manipulate animations.

BUG=741076

Review-Url: https://codereview.chromium.org/2976873003
Cr-Commit-Position: refs/heads/master@{#486887}

ui/gfx/BUILD.gn

@@ -578,6 +578,8 @@ component("gfx_switches") {
 static_library("test_support") {
   testonly = true
   sources = [
+    "animation/animation_test_api.cc",
+    "animation/animation_test_api.h",
     "animation/test_animation_delegate.h",
     "geometry/test/rect_test_util.cc",
     "geometry/test/rect_test_util.h",

ui/gfx/animation/animation.h

@@ -19,6 +19,7 @@ namespace gfx {
 
 class AnimationContainer;
 class AnimationDelegate;
+class AnimationTestApi;
 
 // Base class used in implementing animations. You only need use this class if
 // you're implementing a new animation type, otherwise you'll likely want one of
@@ -92,6 +93,8 @@ class ANIMATION_EXPORT Animation : public AnimationContainerElement {
   base::TimeDelta GetTimerInterval() const override;
 
  private:
+  friend class AnimationTestApi;
+
   // Interval for the animation.
   const base::TimeDelta timer_interval_;
 

ui/gfx/animation/animation_test_api.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/gfx/animation/animation_test_api.h"
+
+#include "base/time/time.h"
+#include "ui/gfx/animation/animation.h"
+
+namespace gfx {
+
+AnimationTestApi::AnimationTestApi(Animation* animation)
+    : animation_(animation) {}
+
+AnimationTestApi::~AnimationTestApi() {}
+
+void AnimationTestApi::SetStartTime(base::TimeTicks ticks) {
+  animation_->SetStartTime(ticks);
+}
+
+void AnimationTestApi::Step(base::TimeTicks ticks) {
+  animation_->Step(ticks);
+}
+
+}  // namespace gfx

ui/gfx/animation/animation_test_api.h

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef UI_GFX_ANIMATION_ANIMATION_TEST_API_H_
+#define UI_GFX_ANIMATION_ANIMATION_TEST_API_H_
+
+#include "base/macros.h"
+#include "ui/gfx/animation/animation.h"
+
+namespace gfx {
+
+// Class to provide access to Animation internals for testing.
+class AnimationTestApi {
+ public:
+  explicit AnimationTestApi(Animation* animation);
+  ~AnimationTestApi();
+
+  // Sets the start of the animation.
+  void SetStartTime(base::TimeTicks ticks);
+
+  // Manually steps the animation forward
+  void Step(base::TimeTicks ticks);
+
+ private:
+  Animation* animation_;
+
+  DISALLOW_COPY_AND_ASSIGN(AnimationTestApi);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_ANIMATION_ANIMATION_TEST_API_H_

ui/gfx/animation/slide_animation_unittest.cc

@@ -10,32 +10,14 @@
 #include "base/test/scoped_task_environment.h"
 #include "base/time/time.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "ui/gfx/animation/animation_test_api.h"
 #include "ui/gfx/animation/test_animation_delegate.h"
 
 namespace gfx {
 
-// Class to provide access to SlideAnimation internals for testing.
-class SlideAnimation::TestApi {
- public:
-  explicit TestApi(SlideAnimation* animation) : animation_(animation) {}
-
-  void SetStartTime(base::TimeTicks ticks) {
-    animation_->SetStartTime(ticks);
-  }
-
-  void Step(base::TimeTicks ticks) {
-    animation_->Step(ticks);
-  }
-
- private:
-  SlideAnimation* animation_;
-
-  DISALLOW_COPY_AND_ASSIGN(TestApi);
-};
-
 ////////////////////////////////////////////////////////////////////////////////
 // SlideAnimationTest
-class SlideAnimationTest: public testing::Test {
+class SlideAnimationTest : public testing::Test {
  protected:
   SlideAnimationTest()
       : scoped_task_environment_(
@@ -62,7 +44,7 @@ TEST_F(SlideAnimationTest, InitialState) {
 
 TEST_F(SlideAnimationTest, Basics) {
   SlideAnimation animation(nullptr);
-  SlideAnimation::TestApi test_api(&animation);
+  AnimationTestApi test_api(&animation);
 
   // Use linear tweening to make the math easier below.
   animation.SetTweenType(Tween::LINEAR);