Make scrollbars scroll on main thread.

BUG=139396
TEST=ScrollbarLayerTest.shouldScrollNonOverlayOnMainThread

Review URL: https://chromiumcodereview.appspot.com/11358151

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@174235 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 61 insertions, 16 deletions

diff --git a/cc/scrollbar_layer.cc b/cc/scrollbar_layer.cc
index c4e61ac..f35b865 100644
--- a/cc/scrollbar_layer.cc
+++ b/cc/scrollbar_layer.cc
@@ -40,6 +40,8 @@ ScrollbarLayer::ScrollbarLayer(
     , m_scrollLayerId(scrollLayerId)
     , m_textureFormat(GL_INVALID_ENUM)
 {
+    if (!m_scrollbar->isOverlay())
+        setShouldScrollOnMainThread(true);
 }
 
 ScrollbarLayer::~ScrollbarLayer()
diff --git a/cc/scrollbar_layer_unittest.cc b/cc/scrollbar_layer_unittest.cc
index 3446681..1c3bcfb 100644
--- a/cc/scrollbar_layer_unittest.cc
+++ b/cc/scrollbar_layer_unittest.cc
@@ -22,6 +22,19 @@
 namespace cc {
 namespace {
 
+scoped_ptr<LayerImpl> layerImplForScrollAreaAndScrollbar(
+    FakeLayerTreeHostImpl* host_impl,
+    scoped_ptr<WebKit::WebScrollbar> scrollbar,
+    bool reverse_order)
+{
+    scoped_refptr<Layer> layerTreeRoot = Layer::create();
+    scoped_refptr<Layer> child1 = Layer::create();
+    scoped_refptr<Layer> child2 = ScrollbarLayer::create(scrollbar.Pass(), FakeScrollbarThemePainter::Create(false).PassAs<ScrollbarThemePainter>(), FakeWebScrollbarThemeGeometry::create(), child1->id());
+    layerTreeRoot->addChild(child1);
+    layerTreeRoot->insertChild(child2, reverse_order ? 0 : 1);
+    return TreeSynchronizer::synchronizeTrees(layerTreeRoot.get(), scoped_ptr<LayerImpl>(), host_impl->activeTree()).Pass();
+}
+
 TEST(ScrollbarLayerTest, resolveScrollLayerPointer)
 {
     FakeImplProxy proxy;
@@ -29,13 +42,7 @@ TEST(ScrollbarLayerTest, resolveScrollLayerPointer)
 
     {
         scoped_ptr<WebKit::WebScrollbar> scrollbar(FakeWebScrollbar::create());
-        scoped_refptr<Layer> layerTreeRoot = Layer::create();
-        scoped_refptr<Layer> child1 = Layer::create();
-        scoped_refptr<Layer> child2 = ScrollbarLayer::create(scrollbar.Pass(), FakeScrollbarThemePainter::Create(false).PassAs<ScrollbarThemePainter>(), FakeWebScrollbarThemeGeometry::create(), child1->id());
-        layerTreeRoot->addChild(child1);
-        layerTreeRoot->addChild(child2);
-
-        scoped_ptr<LayerImpl> layerImplTreeRoot = TreeSynchronizer::synchronizeTrees(layerTreeRoot.get(), scoped_ptr<LayerImpl>(), hostImpl.activeTree());
+        scoped_ptr<LayerImpl> layerImplTreeRoot = layerImplForScrollAreaAndScrollbar(&hostImpl, scrollbar.Pass(), false);
 
         LayerImpl* ccChild1 = layerImplTreeRoot->children()[0];
         ScrollbarLayerImpl* ccChild2 = static_cast<ScrollbarLayerImpl*>(layerImplTreeRoot->children()[1]);
@@ -46,13 +53,7 @@ TEST(ScrollbarLayerTest, resolveScrollLayerPointer)
 
     { // another traverse order
         scoped_ptr<WebKit::WebScrollbar> scrollbar(FakeWebScrollbar::create());
-        scoped_refptr<Layer> layerTreeRoot = Layer::create();
-        scoped_refptr<Layer> child2 = Layer::create();
-        scoped_refptr<Layer> child1 = ScrollbarLayer::create(scrollbar.Pass(), FakeScrollbarThemePainter::Create(false).PassAs<ScrollbarThemePainter>(), FakeWebScrollbarThemeGeometry::create(), child2->id());
-        layerTreeRoot->addChild(child1);
-        layerTreeRoot->addChild(child2);
-
-        scoped_ptr<LayerImpl> layerImplTreeRoot = TreeSynchronizer::synchronizeTrees(layerTreeRoot.get(), scoped_ptr<LayerImpl>(), hostImpl.activeTree());
+        scoped_ptr<LayerImpl> layerImplTreeRoot = layerImplForScrollAreaAndScrollbar(&hostImpl, scrollbar.Pass(), true);
 
         ScrollbarLayerImpl* ccChild1 = static_cast<ScrollbarLayerImpl*>(layerImplTreeRoot->children()[0]);
         LayerImpl* ccChild2 = layerImplTreeRoot->children()[1];
@@ -62,6 +63,34 @@ TEST(ScrollbarLayerTest, resolveScrollLayerPointer)
     }
 }
 
+TEST(ScrollbarLayerTest, shouldScrollNonOverlayOnMainThread)
+{
+    FakeImplProxy proxy;
+    FakeLayerTreeHostImpl hostImpl(&proxy);
+
+    // Create and attach a non-overlay scrollbar.
+    scoped_ptr<WebKit::WebScrollbar> scrollbar(FakeWebScrollbar::create());
+    static_cast<FakeWebScrollbar*>(scrollbar.get())->setOverlay(false);
+    scoped_ptr<LayerImpl> layerImplTreeRoot = layerImplForScrollAreaAndScrollbar(&hostImpl, scrollbar.Pass(), false);
+    ScrollbarLayerImpl* scrollbarLayerImpl = static_cast<ScrollbarLayerImpl*>(layerImplTreeRoot->children()[1]);
+
+    // When the scrollbar is not an overlay scrollbar, the scroll should be
+    // responded to on the main thread as the compositor does not yet implement
+    // scrollbar scrolling.
+    EXPECT_EQ(InputHandlerClient::ScrollOnMainThread, scrollbarLayerImpl->tryScroll(gfx::Point(0, 0), InputHandlerClient::Gesture));
+
+    // Create and attach an overlay scrollbar.
+    scrollbar = FakeWebScrollbar::create();
+    static_cast<FakeWebScrollbar*>(scrollbar.get())->setOverlay(true);
+
+    layerImplTreeRoot = layerImplForScrollAreaAndScrollbar(&hostImpl, scrollbar.Pass(), false);
+    scrollbarLayerImpl = static_cast<ScrollbarLayerImpl*>(layerImplTreeRoot->children()[1]);
+
+    // The user shouldn't be able to drag an overlay scrollbar and the scroll
+    // may be handled in the compositor.
+    EXPECT_EQ(InputHandlerClient::ScrollIgnored, scrollbarLayerImpl->tryScroll(gfx::Point(0, 0), InputHandlerClient::Gesture));
+}
+
 TEST(ScrollbarLayerTest, scrollOffsetSynchronization)
 {
     FakeImplProxy proxy;
@@ -132,7 +161,7 @@ public:
 
     virtual void commitCompleteOnThread(LayerTreeHostImpl* impl) OVERRIDE
     {
-        const int kMaxTextureSize = m_layerTreeHost->rendererCapabilities().maxTextureSize;
+        const int kMaxTextureSize = impl->rendererCapabilities().maxTextureSize;
 
         // Check first that we're actually testing something.
         EXPECT_GT(m_scrollbarLayer->bounds().width(), kMaxTextureSize);
diff --git a/cc/test/fake_web_scrollbar.cc b/cc/test/fake_web_scrollbar.cc
index eafda67..3b770a2 100644
--- a/cc/test/fake_web_scrollbar.cc
+++ b/cc/test/fake_web_scrollbar.cc
@@ -6,8 +6,12 @@
 
 namespace cc {
 
+void FakeWebScrollbar::setOverlay(bool isOverlay) {
+  m_isOverlay = isOverlay;
+}
+
 bool FakeWebScrollbar::isOverlay() const {
-  return false;
+  return m_isOverlay;
 }
 
 int FakeWebScrollbar::value() const {
@@ -66,4 +70,7 @@ WebKit::WebScrollbar::Orientation FakeWebScrollbar::orientation() const {
   return WebScrollbar::Horizontal;
 }
 
+FakeWebScrollbar::FakeWebScrollbar() : m_isOverlay(false) {
+}
+
 }  // namespace cc
diff --git a/cc/test/fake_web_scrollbar.h b/cc/test/fake_web_scrollbar.h
index 4d8504a..89313d6 100644
--- a/cc/test/fake_web_scrollbar.h
+++ b/cc/test/fake_web_scrollbar.h
@@ -16,6 +16,8 @@ class FakeWebScrollbar : public WebKit::WebScrollbar {
     return make_scoped_ptr(new FakeWebScrollbar());
   }
 
+  void setOverlay(bool isOverlay);
+
   // WebScrollbar implementation
   virtual bool isOverlay() const OVERRIDE;
   virtual int value() const OVERRIDE;
@@ -33,6 +35,11 @@ class FakeWebScrollbar : public WebKit::WebScrollbar {
   virtual ScrollbarOverlayStyle scrollbarOverlayStyle() const OVERRIDE;
   virtual bool isCustomScrollbar() const OVERRIDE;
   virtual Orientation orientation() const OVERRIDE;
+
+ private:
+  FakeWebScrollbar();
+
+  bool m_isOverlay;
 };
 
 }  // namespace cc