Controls offsets computed if either top or bottom are showing

cc/input/browser_controls_offset_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/input/browser_controls_offset_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <memory>
 
@@ skipping 480 matching lines @@
   EXPECT_FLOAT_EQ(0.8f, manager->BottomControlsShownRatio());
   manager->ScrollEnd();
 
   manager->ScrollBegin();
   manager->ScrollBy(gfx::Vector2dF(0.f, -200.f));
   EXPECT_FLOAT_EQ(100.f, manager->ContentBottomOffset());
   EXPECT_FLOAT_EQ(1.f, manager->BottomControlsShownRatio());
   manager->ScrollEnd();
 }
 
+TEST(BrowserControlsOffsetManagerTest,
+     ScrollThenRestoreBottomControlsNoTopControls) {
+  MockBrowserControlsOffsetManagerClient client(0.f, 0.5f, 0.5f);
+  client.SetBottomControlsHeight(100.f);
+  BrowserControlsOffsetManager* manager = client.manager();
+  manager->ScrollBegin();
+  manager->ScrollBy(gfx::Vector2dF(0.f, 20.f));
+  EXPECT_FLOAT_EQ(80.f, manager->ContentBottomOffset());
+  EXPECT_FLOAT_EQ(0.8f, manager->BottomControlsShownRatio());
+  manager->ScrollEnd();
+
+  manager->ScrollBegin();
+  manager->ScrollBy(gfx::Vector2dF(0.f, -200.f));
+  EXPECT_FLOAT_EQ(100.f, manager->ContentBottomOffset());
+  EXPECT_FLOAT_EQ(1.f, manager->BottomControlsShownRatio());
+  manager->ScrollEnd();
+}
+
 TEST(BrowserControlsOffsetManagerTest, HideAndPeekBottomControls) {
   MockBrowserControlsOffsetManagerClient client(100.f, 0.5f, 0.5f);
   client.SetBottomControlsHeight(100.f);
   BrowserControlsOffsetManager* manager = client.manager();
   manager->ScrollBegin();
   manager->ScrollBy(gfx::Vector2dF(0.f, 300.f));
   EXPECT_FLOAT_EQ(0.f, manager->ContentBottomOffset());
   EXPECT_FLOAT_EQ(0.f, manager->BottomControlsShownRatio());
   manager->ScrollEnd();
 
@@ skipping 15 matching lines @@
   EXPECT_TRUE(manager->has_animation());
   EXPECT_FLOAT_EQ(1.f, client.CurrentBrowserControlsShownRatio());
 
   manager->UpdateBrowserControlsState(BOTH, SHOWN, true);
   EXPECT_FALSE(manager->has_animation());
   EXPECT_FLOAT_EQ(1.f, client.CurrentBrowserControlsShownRatio());
 }
 
 }  // namespace
 }  // namespace cc