Controls offsets computed if either top or bottom are showing

cc/input/browser_controls_offset_manager_unittest.cc

Index: cc/input/browser_controls_offset_manager_unittest.cc
diff --git a/cc/input/browser_controls_offset_manager_unittest.cc b/cc/input/browser_controls_offset_manager_unittest.cc
index 84b37cd8aea3b8411dc244a36eb4d2da99c462b3..a320e6573e658e864a7b0419886fb8b9e1132e70 100644
--- a/cc/input/browser_controls_offset_manager_unittest.cc
+++ b/cc/input/browser_controls_offset_manager_unittest.cc
@@ -498,6 +498,24 @@ TEST(BrowserControlsOffsetManagerTest, ScrollThenRestoreBottomControls) {
   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);