cc: Allow 'overflow: hidden' layers to be scrolled again.

Disabling scroll of 'overflow: hidden' layers break sites when user zooms in. So allow
scrolling such layers until a better fox for panning in zoomed content is available.

BUG=322223
R=aelias@chromium.org

Review URL: https://codereview.chromium.org/109343003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239675 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 7 insertions, 20 deletions

diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index e46f4db..f60ae81 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -358,16 +358,6 @@ void LayerImpl::SetSentScrollDelta(gfx::Vector2d sent_scroll_delta) {
 
 gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
   DCHECK(scrollable());
-  gfx::Vector2dF scroll_hidden;
-  if (!user_scrollable_horizontal_) {
-    scroll_hidden.set_x(scroll.x());
-    scroll.set_x(0.f);
-  }
-  if (!user_scrollable_vertical_) {
-    scroll_hidden.set_y(scroll.y());
-    scroll.set_y(0.f);
-  }
-
   gfx::Vector2dF min_delta = -scroll_offset_;
   gfx::Vector2dF max_delta = max_scroll_offset_ - scroll_offset_;
   // Clamp new_delta so that position + delta stays within scroll bounds.
@@ -375,7 +365,7 @@ gfx::Vector2dF LayerImpl::ScrollBy(gfx::Vector2dF scroll) {
   new_delta.SetToMax(min_delta);
   new_delta.SetToMin(max_delta);
   gfx::Vector2dF unscrolled =
-      ScrollDelta() + scroll + scroll_hidden - new_delta;
+      ScrollDelta() + scroll - new_delta;
   SetScrollDelta(new_delta);
   return unscrolled;
 }
@@ -476,13 +466,6 @@ InputHandler::ScrollStatus LayerImpl::TryScroll(
     return InputHandler::ScrollIgnored;
   }
 
-  if (!user_scrollable_horizontal_ && !user_scrollable_vertical_) {
-    TRACE_EVENT0("cc",
-                 "LayerImpl::TryScroll: Ignored. User gesture is not allowed"
-                 " to scroll this layer.");
-    return InputHandler::ScrollIgnored;
-  }
-
   return InputHandler::ScrollStarted;
 }
 
diff --git a/cc/layers/layer_impl_unittest.cc b/cc/layers/layer_impl_unittest.cc
index c43adff..9d90c04 100644
--- a/cc/layers/layer_impl_unittest.cc
+++ b/cc/layers/layer_impl_unittest.cc
@@ -566,7 +566,9 @@ TEST_F(LayerImplScrollTest, ApplySentScrollsWithAcceptingDelegate) {
   EXPECT_VECTOR_EQ(gfx::Vector2d(), layer()->sent_scroll_delta());
 }
 
-TEST_F(LayerImplScrollTest, ScrollUserUnscrollableLayer) {
+// The user-scrollability breaks for zoomed-in pages. So disable this.
+// http://crbug.com/322223
+TEST_F(LayerImplScrollTest, DISABLED_ScrollUserUnscrollableLayer) {
   gfx::Vector2d max_scroll_offset(50, 80);
   gfx::Vector2d scroll_offset(10, 5);
   gfx::Vector2dF scroll_delta(20.5f, 8.5f);
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 3a1cf8d..59ee586 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -731,7 +731,9 @@ TEST_F(LayerTreeHostImplTest, ScrollVerticallyByPageReturnsCorrectValue) {
       gfx::Point(), SCROLL_BACKWARD));
 }
 
-TEST_F(LayerTreeHostImplTest, ScrollWithUserUnscrollableLayers) {
+// The user-scrollability breaks for zoomed-in pages. So disable this.
+// http://crbug.com/322223
+TEST_F(LayerTreeHostImplTest, DISABLED_ScrollWithUserUnscrollableLayers) {
   LayerImpl* scroll_layer = SetupScrollAndContentsLayers(gfx::Size(200, 200));
   host_impl_->SetViewportSize(gfx::Size(100, 100));