Touch flings should not bubble.

Currently touch flings can bubble out of an accelerated overflow scrolling div,
but this should not happen.

Looking at InputHandlerProxy::HandleGestureFling, FlingScrollBegin appears to be used for touch fling. Given that this is the case, I've set should_bubble_scrolls_ to false there.

Tests:
TouchFlingShouldNotBubble
 - checks that this fling doesn't bubble.
WheelFlingShouldBubble
 - checks that this does.

R=danakj@chromium.org,aelias@chromium.org
BUG=270281

Review URL: https://codereview.chromium.org/26470004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@227585 0039d316-1c4b-4281-b951-d872f2087c98

cc/trees/layer_tree_host_impl.cc

@@ -2267,6 +2267,9 @@ InputHandler::ScrollStatus LayerTreeHostImpl::FlingScrollBegin() {
     return ScrollIgnored;
   }
 
+  if (!wheel_scrolling_)
+    should_bubble_scrolls_ = false;
+
   return ScrollStarted;
 }
 

cc/trees/layer_tree_host_impl_unittest.cc

@@ -195,7 +195,7 @@ class LayerTreeHostImplTest : public testing::Test,
       times_encountered++;
     }
 
-    ASSERT_EQ(times_encountered, 1);
+    ASSERT_EQ(1, times_encountered);
   }
 
   static void ExpectNone(const ScrollAndScaleSet& scroll_info, int id) {
@@ -5306,5 +5306,81 @@ TEST_F(LayerTreeHostImplTest, ShutdownReleasesContext) {
   EXPECT_EQ(0u, context_provider->TestContext3d()->NumTextures());
 }
 
+TEST_F(LayerTreeHostImplTest, TouchFlingShouldNotBubble) {
+  // When flinging via touch, only the child should scroll (we should not
+  // bubble).
+  gfx::Size surface_size(10, 10);
+  gfx::Size content_size(20, 20);
+  scoped_ptr<LayerImpl> root = CreateScrollableLayer(1, content_size);
+  scoped_ptr<LayerImpl> child = CreateScrollableLayer(2, content_size);
+
+  root->AddChild(child.Pass());
+
+  host_impl_->SetViewportSize(surface_size);
+  host_impl_->active_tree()->SetRootLayer(root.Pass());
+  host_impl_->active_tree()->DidBecomeActive();
+  InitializeRendererAndDrawFrame();
+  {
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->ScrollBegin(gfx::Point(),
+                                      InputHandler::Gesture));
+
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->FlingScrollBegin());
+
+    gfx::Vector2d scroll_delta(0, 100);
+    host_impl_->ScrollBy(gfx::Point(), scroll_delta);
+    host_impl_->ScrollBy(gfx::Point(), scroll_delta);
+
+    host_impl_->ScrollEnd();
+
+    scoped_ptr<ScrollAndScaleSet> scroll_info =
+        host_impl_->ProcessScrollDeltas();
+
+    // Only the child should have scrolled.
+    ASSERT_EQ(1u, scroll_info->scrolls.size());
+    ExpectNone(*scroll_info.get(),
+               host_impl_->active_tree()->root_layer()->id());
+  }
+}
+
+TEST_F(LayerTreeHostImplTest, WheelFlingShouldBubble) {
+  // When flinging via wheel, the root should eventually scroll (we should
+  // bubble).
+  gfx::Size surface_size(10, 10);
+  gfx::Size content_size(20, 20);
+  scoped_ptr<LayerImpl> root = CreateScrollableLayer(1, content_size);
+  scoped_ptr<LayerImpl> child = CreateScrollableLayer(2, content_size);
+
+  root->AddChild(child.Pass());
+
+  host_impl_->SetViewportSize(surface_size);
+  host_impl_->active_tree()->SetRootLayer(root.Pass());
+  host_impl_->active_tree()->DidBecomeActive();
+  InitializeRendererAndDrawFrame();
+  {
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->ScrollBegin(gfx::Point(), InputHandler::Wheel));
+
+    EXPECT_EQ(InputHandler::ScrollStarted,
+              host_impl_->FlingScrollBegin());
+
+    gfx::Vector2d scroll_delta(0, 100);
+    host_impl_->ScrollBy(gfx::Point(), scroll_delta);
+    host_impl_->ScrollBy(gfx::Point(), scroll_delta);
+
+    host_impl_->ScrollEnd();
+
+    scoped_ptr<ScrollAndScaleSet> scroll_info =
+        host_impl_->ProcessScrollDeltas();
+
+    // Only the root should have scrolled.
+    ASSERT_EQ(2u, scroll_info->scrolls.size());
+    ExpectContains(*scroll_info.get(),
+                   host_impl_->active_tree()->root_layer()->id(),
+                   gfx::Vector2d(0, 10));
+  }
+}
+
 }  // namespace
 }  // namespace cc