Tiling priorities 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 94b8bfa1cfac7e9daaa5cef94a4e41954d7a8880..3e3593b648008f310d14914c9e534c5a2971944a 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -66,6 +66,7 @@
 #include "cc/trees/tree_synchronizer.h"
 #include "gpu/GLES2/gl2extchromium.h"
 #include "ui/gfx/frame_time.h"
+#include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/size_conversions.h"
 #include "ui/gfx/vector2d_conversions.h"
 
@@ -1345,15 +1346,29 @@ void LayerTreeHostImpl::SetExternalDrawConstraints(
     const gfx::Transform& transform,
     const gfx::Rect& viewport,
     const gfx::Rect& clip,
+    const gfx::Rect& external_tiling_rect,
+    const gfx::Transform& external_tiling_transform,

[enne (OOO), 2014/07/25 18:44:30]

Does cc even need to know about external_tiling_transform? Can the caller do
this inverse since it's also handing in the external_tiling_rect?

     bool resourceless_software_draw) {
+  gfx::Rect viewport_rect_for_tile_priority;
+  if (!resourceless_software_draw_) {
+    gfx::Transform screen_to_view(gfx::Transform::kSkipInitialization);
+    if (external_tiling_transform.GetInverse(&screen_to_view)) {
+      // Convert from screen space to view space.
+      viewport_rect_for_tile_priority = gfx::ToEnclosingRect(
+          MathUtil::ProjectClippedRect(screen_to_view, external_tiling_rect));
+    }
+  }
+
   if (external_transform_ != transform || external_viewport_ != viewport ||
-      resourceless_software_draw_ != resourceless_software_draw) {
+      resourceless_software_draw_ != resourceless_software_draw ||
+      viewport_rect_for_tile_priority_ != viewport_rect_for_tile_priority) {
     active_tree_->set_needs_update_draw_properties();
   }
 
   external_transform_ = transform;
   external_viewport_ = viewport;
   external_clip_ = clip;
+  viewport_rect_for_tile_priority_ = viewport_rect_for_tile_priority;
   resourceless_software_draw_ = resourceless_software_draw;
 }
 
@@ -2162,6 +2177,10 @@ void LayerTreeHostImpl::SetDeviceScaleFactor(float device_scale_factor) {
   SetFullRootLayerDamage();
 }
 
+const gfx::Rect LayerTreeHostImpl::ViewportRectForTilePriority() const {
+  return viewport_rect_for_tile_priority_;
+}
+
 gfx::Size LayerTreeHostImpl::DrawViewportSize() const {
   return DeviceViewport().size();
 }