Tiling priorities in Android Webview.

cc/output/output_surface.h

Index: cc/output/output_surface.h
diff --git a/cc/output/output_surface.h b/cc/output/output_surface.h
index 07c0f262f5552c362d8205ef0129ccfb4b6c9159..e8eff5e6ea6900eaf7309405677448ba50e1645b 100644
--- a/cc/output/output_surface.h
+++ b/cc/output/output_surface.h
@@ -163,10 +163,13 @@ class CC_EXPORT OutputSurface {
   void ReclaimResources(const CompositorFrameAck* ack);
   void DidLoseOutputSurface();
   void SetExternalStencilTest(bool enabled);
-  void SetExternalDrawConstraints(const gfx::Transform& transform,
-                                  const gfx::Rect& viewport,
-                                  const gfx::Rect& clip,
-                                  bool resourceless_software_draw);
+  void SetExternalDrawConstraints(
+      const gfx::Transform& transform,
+      const gfx::Rect& viewport,
+      const gfx::Rect& clip,
+      const gfx::Rect& external_tiling_rect,

[enne (OOO), 2014/07/25 19:16:55]

In general this patch looks fine to me, but I still am bikeshedding a little on
external_tiling_rect and external_tiling_transform as names.  The name "tiling"
just doesn't really mean anything and is ambiguous with other uses of "tiling"
in cc.

Are there other names that could work here? One suggestion:
external_viewport_rect and external_viewport_transform make slightly more sense
to me.  "external" because they're not applied to quads in the same way that
transform/viewport in this function are?

Maybe a comment on this function about how these two parameters differ from
transform/viewport would help too?

[hush (inactive), 2014/07/29 00:55:57]

This function name actually suggests all parameters are "external" implicitly.
For example, transform is stored as "external_transform_" in
LTHI::SetExternalDrawConstraints.

So how about I make it verbose and consistent with what we use in
picture_layer_impl: viewport_rect_for_tile_priority and
transform_for_tile_priority

There are already comments in LTHI private members (external_transform_, 
external_viewport, etc.). Are those comments enough?

On 2014/07/25 19:16:55, enne wrote:

[enne (OOO), 2014/07/29 18:39:28]

"_for_tile_priority" is definitely better than "tiling", thanks.  And
consistency in variable naming all the way through also seems good.

Those comments are probably enough.

+      const gfx::Transform& external_tiling_transform,
+      bool resourceless_software_draw);
 
  private:
   void SetUpContext3d();