Hide scrollbars when their dimensions are not scrollable.

cc/animation/scrollbar_animation_controller_thinning_unittest.cc

 // Copyright 2013 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 "cc/animation/scrollbar_animation_controller_thinning.h"
 
 #include "cc/layers/solid_color_scrollbar_layer_impl.h"
 #include "cc/test/fake_impl_proxy.h"
 #include "cc/test/fake_layer_tree_host_impl.h"
+#include "cc/test/geometry_test_utils.h"
 #include "cc/test/test_shared_bitmap_manager.h"
+#include "cc/trees/layer_tree_impl.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace cc {
 namespace {
 
 class ScrollbarAnimationControllerThinningTest
     : public testing::Test,
       public ScrollbarAnimationControllerClient {
  public:
   ScrollbarAnimationControllerThinningTest()
@@ skipping 24 matching lines @@
                                              kId,
                                              HORIZONTAL,
                                              kThumbThickness,
                                              kTrackStart,
                                              kIsLeftSideVerticalScrollbar,
                                              kIsOverlayScrollbar);
 
     scrollbar_layer_->SetScrollLayerAndClipLayerByIds(scroll_layer_ptr->id(),
                                                       clip_layer_->id());
     clip_layer_->SetBounds(gfx::Size(100, 100));
-    scroll_layer_ptr->SetBounds(gfx::Size(50, 50));
+    scroll_layer_ptr->SetBounds(gfx::Size(200, 200));
 
     scrollbar_controller_ = ScrollbarAnimationControllerThinning::Create(
         scroll_layer_ptr,
         this,
         base::TimeDelta::FromSeconds(2),
         base::TimeDelta::FromSeconds(5),
         base::TimeDelta::FromSeconds(3));
   }
 
   FakeImplProxy proxy_;
   TestSharedBitmapManager shared_bitmap_manager_;
   FakeLayerTreeHostImpl host_impl_;
   scoped_ptr<ScrollbarAnimationControllerThinning> scrollbar_controller_;
   scoped_ptr<LayerImpl> clip_layer_;
   scoped_ptr<SolidColorScrollbarLayerImpl> scrollbar_layer_;
 
   base::Closure start_fade_;
 };
 
 // Check initialization of scrollbar.
 TEST_F(ScrollbarAnimationControllerThinningTest, Idle) {
   scrollbar_controller_->Animate(base::TimeTicks());
   EXPECT_FLOAT_EQ(0.7f, scrollbar_layer_->opacity());
   EXPECT_FLOAT_EQ(0.4f, scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
+// Check that scrollbar disappears when the layer becomes non-scrollable.
+TEST_F(ScrollbarAnimationControllerThinningTest, HideOnResize) {
+  LayerImpl* scroll_layer = host_impl_.active_tree()->LayerById(1);
+  ASSERT_TRUE(scroll_layer);
+  EXPECT_SIZE_EQ(gfx::Size(200, 200), scroll_layer->bounds());
+
+  EXPECT_EQ(HORIZONTAL, scrollbar_layer_->orientation());
+
+  // Shrink along X axis, horizontal scrollbar should appear.
+  clip_layer_->SetBounds(gfx::Size(100, 200));
+  EXPECT_SIZE_EQ(gfx::Size(100, 200), clip_layer_->bounds());
+
+  scrollbar_controller_->DidScrollBegin();
+
+  scrollbar_controller_->DidScrollUpdate(false);
+  EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->opacity());
+
+  scrollbar_controller_->DidScrollEnd();
+
+  // Shrink along Y axis and expand along X, horizontal scrollbar
+  // should disappear.
+  clip_layer_->SetBounds(gfx::Size(200, 100));
+  EXPECT_SIZE_EQ(gfx::Size(200, 100), clip_layer_->bounds());
+
+  scrollbar_controller_->DidScrollBegin();
+
+  scrollbar_controller_->DidScrollUpdate(false);
+  EXPECT_FLOAT_EQ(0.0f, scrollbar_layer_->opacity());
+
+  scrollbar_controller_->DidScrollEnd();
+}
+
 // Scroll content. Confirm the scrollbar gets dark and then becomes light
 // after stopping.
 TEST_F(ScrollbarAnimationControllerThinningTest, AwakenByProgrammaticScroll) {
   base::TimeTicks time;
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->DidScrollUpdate(false);
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->opacity());
   // Scrollbar doesn't change size if triggered by scroll.
   EXPECT_FLOAT_EQ(0.4f, scrollbar_layer_->thumb_thickness_scale_factor());
 
@@ skipping 239 matching lines @@
 
   time += base::TimeDelta::FromSeconds(1);
   scrollbar_controller_->Animate(time);
   EXPECT_FLOAT_EQ(0.7f, scrollbar_layer_->opacity());
   // The thickness now gets big again.
   EXPECT_FLOAT_EQ(1.0f, scrollbar_layer_->thumb_thickness_scale_factor());
 }
 
 }  // namespace
 }  // namespace cc