Implement transform/clip support for 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 f58f3c2d7add8598fe445712494c94050ceaebcd..c1221d0d6fa32bed43981e4420d4d65e131d2649 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1035,6 +1035,12 @@ void LayerTreeHostImpl::SetManagedMemoryPolicy(
     client_->SetNeedsCommitOnImplThread();
 }
 
+void LayerTreeHostImpl::SetDeviceTransformAndClip(gfx::Transform transform,
+                                                  gfx::Rect clip) {
+  device_transform_ = transform;
+  device_clip_ = clip;
+}
+
 void LayerTreeHostImpl::SetNeedsRedrawRect(gfx::Rect damage_rect) {
   client_->SetNeedsRedrawRectOnImplThread(damage_rect);
 }
@@ -1516,6 +1522,23 @@ void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
   SetFullRootLayerDamage();
 }
 
+gfx::Rect LayerTreeHostImpl::DeviceClip() const {
+  if (device_clip_.IsEmpty())
+    return gfx::Rect(device_viewport_size_);
+
+  return device_clip_;
+}
+
+gfx::Transform LayerTreeHostImpl::DeviceTransform() const {
+  gfx::Transform device_transform = device_transform_;
+  device_transform.Scale(device_scale_factor_, device_scale_factor_);
+  return device_transform;
+}
+
+gfx::Vector2d LayerTreeHostImpl::DeviceViewportOffset() const {
+  return gfx::Vector2d(device_clip_.x(), device_clip_.y());
+}
+
 void LayerTreeHostImpl::UpdateMaxScrollOffset() {
   active_tree_->UpdateMaxScrollOffset();
 }