[Aura] Added Support for rendering software compositor frames as cc::TextureLayers.

ui/compositor/layer.cc

Index: ui/compositor/layer.cc
diff --git a/ui/compositor/layer.cc b/ui/compositor/layer.cc
index 6a3308e08305f5a1da6b0bd4302ba6b9bc4096ed..18ae24808f4a1ab709227c36bca0a50221aca13a 100644
--- a/ui/compositor/layer.cc
+++ b/ui/compositor/layer.cc
@@ -86,6 +86,7 @@ Layer::Layer(LayerType type)
       zoom_(1),
       zoom_inset_(0),
       delegate_(NULL),
+      cc_layer_(NULL),
       scale_content_(true),
       device_scale_factor_(1.0f) {
   CreateWebLayer();
@@ -514,6 +515,25 @@ void Layer::SetExternalTexture(Texture* texture) {
   RecomputeDrawsContentAndUVRect();
 }
 
+void Layer::SetTextureMailbox(const cc::TextureMailbox& mailbox,
+                              float device_scale_factor) {
+  DCHECK_EQ(type_, LAYER_TEXTURED);
+  DCHECK(!solid_color_layer_);
+  layer_updated_externally_ = true;
+  texture_ = NULL;
+  if (!texture_layer_ || !texture_layer_->uses_mailbox()) {
+    scoped_refptr<cc::TextureLayer> new_layer =
+        cc::TextureLayer::CreateForMailbox(this);
+    new_layer->SetFlipped(false);
+    SwitchToLayer(new_layer);
+    texture_layer_ = new_layer;
+  }
+  texture_layer_->SetTextureMailbox(mailbox);
+  mailbox_ = mailbox;
+  mailbox_scale_factor_ = device_scale_factor;
+  RecomputeDrawsContentAndUVRect();
+}

[piman, 2013/05/28 20:58:57]

So, one missing piece here is Window::RecreateLayer. It's used in various UI
animations, for example the cross-fade as we maximize in Ash.
In GL mode, it duplicates the texture.
In the old software mode, it keeps the old layer without causing damage, and
creates a new layer which has the delegate.

As is, the new layer will get the RWHVA as a delegate, but nothing will set the
texture mailbox on it, so it will create a ContentLayer and try to paint it.

One way to go about it is to explicitly duplicate the shm and set it to the new
layer, with proper care wrt destruction.

[slavi, 2013/05/29 18:31:48]

Done.

+
 void Layer::SetDelegatedFrame(scoped_ptr<cc::DelegatedFrameData> frame,
                               gfx::Size frame_size_in_dip) {
   DCHECK_EQ(type_, LAYER_TEXTURED);
@@ -636,12 +656,16 @@ void Layer::PaintContents(SkCanvas* sk_canvas,
 
 unsigned Layer::PrepareTexture(cc::ResourceUpdateQueue* queue) {
   DCHECK(texture_layer_);
-  return texture_->PrepareTexture();
+  if (texture_)
+    return texture_->PrepareTexture();
+  return 0;
 }
 
 WebKit::WebGraphicsContext3D* Layer::Context3d() {
   DCHECK(texture_layer_);
-  return texture_->HostContext3D();
+  if (texture_)
+    return texture_->HostContext3D();
+  return NULL;
 }
 
 bool Layer::PrepareTextureMailbox(cc::TextureMailbox* mailbox) {
@@ -919,11 +943,17 @@ void Layer::RecomputeDrawsContentAndUVRect() {
   DCHECK(cc_layer_);
   gfx::Size size(bounds_.size());
   if (texture_layer_.get()) {
-    DCHECK(texture_);
-
-    float texture_scale_factor = 1.0f / texture_->device_scale_factor();
-    gfx::Size texture_size = gfx::ToFlooredSize(
-        gfx::ScaleSize(texture_->size(), texture_scale_factor));
+    gfx::Size texture_size;
+    if (!texture_layer_->uses_mailbox()) {
+      DCHECK(texture_);
+      float texture_scale_factor = 1.0f / texture_->device_scale_factor();
+      texture_size = gfx::ToFlooredSize(
+          gfx::ScaleSize(texture_->size(), texture_scale_factor));
+    } else {
+      float texture_scale_factor = 1.0f / mailbox_scale_factor_;
+      texture_size = gfx::ToFlooredSize(
+          gfx::ScaleSize(mailbox_.size(), texture_scale_factor));
+    }
     size.ClampToMax(texture_size);
 
     gfx::PointF uv_top_left(0.f, 0.f);