Add a scroll threshold/marker to control hiding/showing top controls.

cc/top_controls_manager_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/top_controls_manager.h"
 
 #include "base/memory/scoped_ptr.h"
 #include "base/time.h"
 #include "cc/layer_impl.h"
 #include "cc/layer_tree_impl.h"
@@ skipping 123 matching lines @@
       client.rootScrollLayer()->scrollDelta() + remaining_scroll);
 
   remaining_scroll = manager->ScrollBy(gfx::Vector2dF(0.f, -50.f));
   EXPECT_EQ(0.f, manager->controls_top_offset());
   EXPECT_EQ(100.f, manager->content_top_offset());
   EXPECT_FALSE(manager->is_overlay_mode());
   client.rootScrollLayer()->setScrollDelta(
       client.rootScrollLayer()->scrollDelta() + remaining_scroll);
 }
 
+TEST(TopControlsManagerTest, ensureScrollThresholdApplied) {
+  MockTopControlsManagerClient client;
+  TopControlsManager* manager = client.manager();
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 200));
+
+  manager->ScrollBegin();
+
+  // Scroll down to hide the controls entirely.
+  manager->ScrollBy(gfx::Vector2dF(0.f, 30.f));
+  EXPECT_EQ(-30.f, manager->controls_top_offset());
+  EXPECT_EQ(70.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 230));
+
+  manager->ScrollBy(gfx::Vector2dF(0.f, 30.f));
+  EXPECT_EQ(-60.f, manager->controls_top_offset());
+  EXPECT_EQ(40.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 260));
+
+  manager->ScrollBy(gfx::Vector2dF(0.f, 100.f));
+  EXPECT_EQ(-100.f, manager->controls_top_offset());
+  EXPECT_EQ(0.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 360));
+
+  // Scroll back up a bit and ensure the controls don't move until we cross
+  // the threshold.
+  manager->ScrollBy(gfx::Vector2dF(0.f, -10.f));
+  EXPECT_EQ(-100.f, manager->controls_top_offset());
+  EXPECT_EQ(0.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 350));
+
+  manager->ScrollBy(gfx::Vector2dF(0.f, -50.f));
+  EXPECT_EQ(-100.f, manager->controls_top_offset());
+  EXPECT_EQ(0.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 300));
+
+  // After hitting the threshold, further scrolling up should result in the top
+  // controls showing.
+  manager->ScrollBy(gfx::Vector2dF(0.f, -10.f));
+  EXPECT_EQ(-90.f, manager->controls_top_offset());
+  EXPECT_EQ(0.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 290));
+
+  manager->ScrollBy(gfx::Vector2dF(0.f, -50.f));
+  EXPECT_EQ(-40.f, manager->controls_top_offset());
+  EXPECT_EQ(0.f, manager->content_top_offset());
+  client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 240));
+
+  manager->ScrollEnd();
+}
+
 TEST(TopControlsManagerTest, partialShownHideAnimation) {
   MockTopControlsManagerClient client;
   TopControlsManager* manager = client.manager();
   client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 300));
   manager->ScrollBy(gfx::Vector2dF(0.f, 300.f));
   EXPECT_EQ(-100.f, manager->controls_top_offset());
   EXPECT_EQ(0.f, manager->content_top_offset());
   EXPECT_TRUE(manager->is_overlay_mode());
 
   client.rootScrollLayer()->setScrollOffset(gfx::Vector2d(0, 270));
@@ skipping 46 matching lines @@
     previous_offset = manager->controls_top_offset();
   }
   EXPECT_FALSE(manager->animation());
   EXPECT_EQ(0.f, manager->controls_top_offset());
   EXPECT_EQ(0.f, manager->content_top_offset());
   EXPECT_TRUE(manager->is_overlay_mode());
 }
 
 }  // namespace
 }  // namespace cc