Clamp compositor's top controls shown ratio on commit from main thread.

cc/trees/layer_tree_host_impl_unittest.cc

 // Copyright 2011 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/trees/layer_tree_host_impl.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <cmath>
@@ skipping 4218 matching lines @@
   host_impl_->top_controls_manager()->ScrollBegin();
   host_impl_->top_controls_manager()->ScrollBy(-top_controls_scroll_delta);
   EXPECT_EQ(top_controls_scroll_delta.y(),
             host_impl_->top_controls_manager()->ContentTopOffset());
   EXPECT_VECTOR_EQ(
       gfx::Vector2dF(0, top_controls_height_ - top_controls_scroll_delta.y()),
       outer_viewport_scroll_layer->FixedContainerSizeDelta());
   host_impl_->top_controls_manager()->ScrollEnd();
 }
 
+// Push a top controls ratio from the main thread that we didn't send as a delta
+// and make sure that the ratio is clamped to the [0, 1] range.
+TEST_F(LayerTreeHostImplTopControlsTest, TopControlsPushUnsentRatio) {
+  SetupTopControlsAndScrollLayerWithVirtualViewport(
+      gfx::Size(10, 50), gfx::Size(10, 50), gfx::Size(10, 100));
+  DrawFrame();
+
+  // Need SetDrawsContent so ScrollBegin's hit test finds an actual layer.
+  LayerImpl* inner_scroll =
+      host_impl_->active_tree()->InnerViewportScrollLayer();
+  inner_scroll->SetDrawsContent(true);
+  LayerImpl* outer_scroll =
+      host_impl_->active_tree()->OuterViewportScrollLayer();
+  outer_scroll->SetDrawsContent(true);
+
+  host_impl_->active_tree()->PushTopControlsFromMainThread(1);
+  ASSERT_EQ(1.0f, host_impl_->active_tree()->CurrentTopControlsShownRatio());
+
+  host_impl_->active_tree()->SetCurrentTopControlsShownRatio(0.5f);
+  ASSERT_EQ(0.5f, host_impl_->active_tree()->CurrentTopControlsShownRatio());
+
+  host_impl_->active_tree()->PushTopControlsFromMainThread(0);
+
+  ASSERT_EQ(0, host_impl_->active_tree()->CurrentTopControlsShownRatio());
+}
+
 // Test that if only the top controls are scrolled, we shouldn't request a
 // commit.
 TEST_F(LayerTreeHostImplTopControlsTest, TopControlsDontTriggerCommit) {
   SetupTopControlsAndScrollLayerWithVirtualViewport(
       gfx::Size(100, 50), gfx::Size(100, 100), gfx::Size(100, 100));
   DrawFrame();
 
   // Show top controls
   EXPECT_EQ(1.f, host_impl_->active_tree()->CurrentTopControlsShownRatio());
 
@@ skipping 6628 matching lines @@
 
   // Re-initialize with a software output surface.
   output_surface_ = FakeOutputSurface::CreateSoftware(
       base::WrapUnique(new SoftwareOutputDevice));
   host_impl_->InitializeRenderer(output_surface_.get());
   EXPECT_FALSE(host_impl_->use_gpu_rasterization());
 }
 
 }  // namespace
 }  // namespace cc