[Android] Disable pull-to-refresh with overflow-y:hidden

Currently, the only way to disable the pull-to-refresh effect is to
explictly preventDefault the causal touches or suppress their default
actions with touch-action: none. However, the latter prevents
any kind of accelerated scrolling, and the former can be to get right
with composed or nested scrollable content.

Use the overflow-y:hidden property on the root element as a signal to
disable the effect. This dovetails with how this property both prevents
hiding of the top controls and suppresses the overscroll glow effect.

BUG=456515,456300

Review URL: https://codereview.chromium.org/910373002

Cr-Commit-Position: refs/heads/master@{#315938}

4 files changed, 35 insertions, 1 deletions

diff --git a/cc/output/compositor_frame_metadata.cc b/cc/output/compositor_frame_metadata.cc
index 039f69d3..dad78a0 100644
--- a/cc/output/compositor_frame_metadata.cc
+++ b/cc/output/compositor_frame_metadata.cc
@@ -10,7 +10,9 @@ CompositorFrameMetadata::CompositorFrameMetadata()
     : device_scale_factor(0.f),
       page_scale_factor(0.f),
       min_page_scale_factor(0.f),
-      max_page_scale_factor(0.f) {
+      max_page_scale_factor(0.f),
+      root_overflow_x_hidden(false),
+      root_overflow_y_hidden(false) {
 }
 
 CompositorFrameMetadata::~CompositorFrameMetadata() {
diff --git a/cc/output/compositor_frame_metadata.h b/cc/output/compositor_frame_metadata.h
index a6fe2d4..e92a84d 100644
--- a/cc/output/compositor_frame_metadata.h
+++ b/cc/output/compositor_frame_metadata.h
@@ -34,6 +34,8 @@ class CC_EXPORT CompositorFrameMetadata {
   gfx::SizeF root_layer_size;
   float min_page_scale_factor;
   float max_page_scale_factor;
+  bool root_overflow_x_hidden;
+  bool root_overflow_y_hidden;
 
   // Used to position the Android location top bar and page content, whose
   // precise position is computed by the renderer compositor.
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index bd77d84..95e1ab1 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1458,6 +1458,16 @@ CompositorFrameMetadata LayerTreeHostImpl::MakeCompositorFrameMetadata() const {
   active_tree_->GetViewportSelection(&metadata.selection_start,
                                      &metadata.selection_end);
 
+  LayerImpl* root_layer_for_overflow = OuterViewportScrollLayer()
+                                           ? OuterViewportScrollLayer()
+                                           : InnerViewportScrollLayer();
+  if (root_layer_for_overflow) {
+    metadata.root_overflow_x_hidden =
+        !root_layer_for_overflow->user_scrollable_horizontal();
+    metadata.root_overflow_y_hidden =
+        !root_layer_for_overflow->user_scrollable_vertical();
+  }
+
   if (!InnerViewportScrollLayer())
     return metadata;
 
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index 23e90e1..4deb8e4 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -1844,6 +1844,8 @@ TEST_F(LayerTreeHostImplTest, CompositorFrameMetadata) {
     EXPECT_EQ(gfx::SizeF(100.f, 100.f), metadata.root_layer_size);
     EXPECT_EQ(0.5f, metadata.min_page_scale_factor);
     EXPECT_EQ(4.f, metadata.max_page_scale_factor);
+    EXPECT_FALSE(metadata.root_overflow_x_hidden);
+    EXPECT_FALSE(metadata.root_overflow_y_hidden);
   }
 
   // Scrolling should update metadata immediately.
@@ -1862,6 +1864,24 @@ TEST_F(LayerTreeHostImplTest, CompositorFrameMetadata) {
     EXPECT_EQ(gfx::Vector2dF(0.f, 10.f), metadata.root_scroll_offset);
   }
 
+  // Root "overflow: hidden" properties should be reflected.
+  {
+    host_impl_->active_tree()
+        ->InnerViewportScrollLayer()
+        ->set_user_scrollable_horizontal(false);
+    CompositorFrameMetadata metadata =
+        host_impl_->MakeCompositorFrameMetadata();
+    EXPECT_TRUE(metadata.root_overflow_x_hidden);
+    EXPECT_FALSE(metadata.root_overflow_y_hidden);
+
+    host_impl_->active_tree()
+        ->InnerViewportScrollLayer()
+        ->set_user_scrollable_vertical(false);
+    metadata = host_impl_->MakeCompositorFrameMetadata();
+    EXPECT_TRUE(metadata.root_overflow_x_hidden);
+    EXPECT_TRUE(metadata.root_overflow_y_hidden);
+  }
+
   // Page scale should update metadata correctly (shrinking only the viewport).
   host_impl_->ScrollBegin(gfx::Point(), InputHandler::Gesture);
   host_impl_->PinchGestureBegin();