Make LayerTreeImpl::ScrollableArea more robust

cc/trees/layer_tree_host_unittest_scroll.cc

 // Copyright 2012 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.h"
 
 #include "cc/layers/content_layer.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
+#include "cc/test/fake_content_layer.h"
 #include "cc/test/fake_content_layer_client.h"
 #include "cc/test/geometry_test_utils.h"
 #include "cc/test/layer_tree_test.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "third_party/WebKit/Source/Platform/chromium/public/WebLayerScrollClient.h"
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/vector2d_conversions.h"
 
 namespace cc {
@@ skipping 634 matching lines @@
 
     EndTest();
   }
 
   virtual void AfterTest() OVERRIDE {}
 };
 
 SINGLE_AND_MULTI_THREAD_TEST_F(
     LayerTreeHostScrollTestScrollZeroMaxScrollOffset);
 
+class LayerTreeHostScrollTestScrollUpdateMaxScrollOffset
+    : public LayerTreeHostScrollTest {
+ public:
+  LayerTreeHostScrollTestScrollUpdateMaxScrollOffset() {}
+
+  virtual void BeginTest() OVERRIDE {
+    PostSetNeedsCommitToMainThread();
+  }
+
+  virtual void SetupTree() OVERRIDE {
+    LayerTreeTest::SetupTree();
+    first_content_layer_ = FakeContentLayer::Create(&client_);
+    first_content_layer_->SetBounds(gfx::Size(1, 256));
+    first_content_layer_->set_layer_animation_delegate(this);
+    layer_tree_host()->root_layer()->AddChild(first_content_layer_);
+    second_content_layer_ = FakeContentLayer::Create(&client_);
+    second_content_layer_->SetBounds(gfx::Size(256, 1));
+    second_content_layer_->set_layer_animation_delegate(this);
+    layer_tree_host()->root_layer()->AddChild(second_content_layer_);
+    layer_tree_host()->root_layer()->SetScrollable(true);
+  }
+
+  virtual void DrawLayersOnThread(LayerTreeHostImpl* impl) OVERRIDE {
+    LayerImpl* root = impl->active_tree()->root_layer();
+    EXPECT_EQ(255, root->max_scroll_offset().x());
+    EXPECT_EQ(255, root->max_scroll_offset().y());
+    EndTest();
+  }
+
+  virtual void AfterTest() OVERRIDE {}
+
+ private:
+  FakeContentLayerClient client_;
+  scoped_refptr<FakeContentLayer> first_content_layer_;
+  scoped_refptr<FakeContentLayer> second_content_layer_;
+};
+
+SINGLE_AND_MULTI_THREAD_TEST_F(
+    LayerTreeHostScrollTestScrollUpdateMaxScrollOffset);
+
 }  // namespace
 }  // namespace cc