Force use of and cache render surface.

cc/trees/damage_tracker.cc

Index: cc/trees/damage_tracker.cc
diff --git a/cc/trees/damage_tracker.cc b/cc/trees/damage_tracker.cc
index d740521408dc7658abb38bfcac7b2dc97c0da96e..51cb25c20e4f34d0fba156b4933aaf351b70a795 100644
--- a/cc/trees/damage_tracker.cc
+++ b/cc/trees/damage_tracker.cc
@@ -26,7 +26,8 @@ std::unique_ptr<DamageTracker> DamageTracker::Create() {
 }
 
 DamageTracker::DamageTracker()
-  : mailboxId_(0) {}
+    : mailboxId_(0),
+      has_property_change_on_contributing_render_surface_(false) {}
 
 DamageTracker::~DamageTracker() {}
 
@@ -258,6 +259,7 @@ DamageTracker::DamageAccumulator DamageTracker::TrackDamageFromSurfaceMask(
 void DamageTracker::PrepareForUpdate() {
   mailboxId_++;
   damage_for_this_update_ = DamageAccumulator();
+  has_property_change_on_contributing_render_surface_ = false;
 }
 
 DamageTracker::DamageAccumulator DamageTracker::TrackDamageFromLeftoverRects() {
@@ -421,6 +423,10 @@ void DamageTracker::AccumulateDamageFromRenderSurface(
       gfx::ToEnclosingRect(render_surface->DrawableContentRect());
   data.Update(surface_rect_in_target_space, mailboxId_);
 
+  has_property_change_on_contributing_render_surface_ |=

[weiliangc, 2017/06/07 21:19:01]

The flag for not able to use the texture should be damage that comes from
contributing layers or contributing surfaces. The damage coming from
contributing layers and contributing render surfaces should just be the
damage_rect on the render surface. Since the damage rect is later set to
output_rect, we should keep track of whether that is empty after damage
calculating and before it is set to output rect.

[wutao, 2017/06/09 02:31:32]

This is a very good point.
Do you mean damage_for_this_update_? I can update
has_damage_from_contributing_render_surface_or_layer at last in
AccumulateDamageFromLayer and AccumulateDamageFromRenderSurface, where all
damage from contributing render surfaces or layers must already have been added
to damage_for_this_update_.

+      render_surface->SurfacePropertyChanged() ||

[weiliangc, 2017/06/07 21:19:01]

SurfacePropertyChanged() seems to be ok for reusing texture, since it's the
surface's own property and ancestor property change.

SUrfacePropertyChanged() is true if there are changes in clip_rect (should be
able to apply to texture), content_rect (shouldn't change in the
force_render_surface state), or changes from ancestor (should be able to handle
in direct renderer when drawing the texture).

[wutao, 2017/06/09 02:31:32]

Acknowledged.

+      render_surface->ContributingRenderSurfacePropertyChanged();
+
   if (surface_is_new || render_surface->SurfacePropertyChanged()) {
     // The entire surface contributes damage.
     damage_for_this_update_.Union(surface_rect_in_target_space);