Fix UpdateTilePriorities viewport in Android WebView.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 870b65d89ba7b123085028c34359d4afbf122131..69372d5f63a8a2702528f9156bb5c376c45d8820 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -195,6 +195,7 @@ LayerTreeHostImpl::LayerTreeHostImpl(
       zero_budget_(false),
       device_scale_factor_(1.f),
       overdraw_bottom_height_(0.f),
+      device_viewport_valid_for_tile_management_(true),
       external_stencil_test_enabled_(false),
       animation_registrar_(AnimationRegistrar::Create()),
       rendering_stats_instrumentation_(rendering_stats_instrumentation),
@@ -291,7 +292,7 @@ bool LayerTreeHostImpl::CanDraw() const {
   if (output_surface_->capabilities().draw_and_swap_full_viewport_every_frame)
     return true;
 
-  if (device_viewport_size_.IsEmpty()) {
+  if (DeviceViewport().IsEmpty()) {
     TRACE_EVENT_INSTANT0("cc", "LayerTreeHostImpl::CanDraw empty viewport",
                          TRACE_EVENT_SCOPE_THREAD);
     return false;
@@ -326,6 +327,9 @@ void LayerTreeHostImpl::ManageTiles() {
     return;
   if (!manage_tiles_needed_)
     return;
+  if (!device_viewport_valid_for_tile_management_)
+    return;
+
   manage_tiles_needed_ = false;
   tile_manager_->ManageTiles();
 
@@ -353,7 +357,7 @@ void LayerTreeHostImpl::StartPageScaleAnimation(gfx::Vector2d target_offset,
   gfx::Vector2dF scroll_total =
       RootScrollLayer()->scroll_offset() + RootScrollLayer()->ScrollDelta();
   gfx::SizeF scaled_scrollable_size = active_tree_->ScrollableSize();
-  gfx::SizeF viewport_size = VisibleViewportSize();
+  gfx::SizeF viewport_size = UnscaledScrollableViewportSize();
 
   double start_time_seconds = (start_time - base::TimeTicks()).InSecondsF();
 
@@ -1160,9 +1164,13 @@ void LayerTreeHostImpl::SetManagedMemoryPolicy(
 
 void LayerTreeHostImpl::SetExternalDrawConstraints(
     const gfx::Transform& transform,
-    gfx::Rect viewport) {
+    gfx::Rect viewport,
+    gfx::Rect clip,
+    bool valid_for_tile_management) {
   external_transform_ = transform;
   external_viewport_ = viewport;
+  external_clip_ = clip;
+  device_viewport_valid_for_tile_management_ = valid_for_tile_management;
 }
 
 void LayerTreeHostImpl::SetExternalStencilTest(bool enabled) {
@@ -1363,7 +1371,7 @@ float LayerTreeHostImpl::DeviceScaleFactor() const {
   return device_scale_factor_;
 }
 
-gfx::SizeF LayerTreeHostImpl::VisibleViewportSize() const {
+gfx::SizeF LayerTreeHostImpl::UnscaledScrollableViewportSize() const {
   // The container layer bounds should be used if non-overlay scrollbars may
   // exist since it adjusts for them.
   LayerImpl* container_layer = active_tree_->RootContainerLayer();
@@ -1374,7 +1382,7 @@ gfx::SizeF LayerTreeHostImpl::VisibleViewportSize() const {
   }
 
   gfx::SizeF dip_size =
-      gfx::ScaleSize(device_viewport_size(), 1.f / device_scale_factor());
+      gfx::ScaleSize(device_viewport_size_, 1.f / device_scale_factor());
 
   float top_offset =
       top_controls_manager_ ? top_controls_manager_->content_top_offset() : 0.f;
@@ -1811,6 +1819,13 @@ gfx::Rect LayerTreeHostImpl::DeviceViewport() const {
   return external_viewport_;
 }
 
+gfx::Rect LayerTreeHostImpl::DeviceClip() const {
+  if (external_clip_.IsEmpty())
+    return DeviceViewport();
+
+  return external_clip_;
+}
+
 const gfx::Transform& LayerTreeHostImpl::DeviceTransform() const {
   return external_transform_;
 }
@@ -2264,7 +2279,7 @@ scoped_ptr<ScrollAndScaleSet> LayerTreeHostImpl::ProcessScrollDeltas() {
 }
 
 void LayerTreeHostImpl::SetFullRootLayerDamage() {
-  SetViewportDamage(gfx::Rect(device_viewport_size_));
+  SetViewportDamage(gfx::Rect(DeviceViewport().size()));
 }
 
 void LayerTreeHostImpl::AnimatePageScale(base::TimeTicks time) {