Add CompositingReasons to compositor layer types.

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index 2ffd61ef4b4243e778a9a0f96bc604c8138fdd08..f48b7483ef670022f801e59c2f3eba0e1c31a091 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -53,6 +53,7 @@ LayerImpl::LayerImpl(LayerTreeImpl* tree_impl, int id)
       force_render_surface_(false),
       is_container_for_fixed_position_layers_(false),
       draw_depth_(0.f),
+      compositing_reasons_(WebKit::CompositingReasonUnknown),
 #ifndef NDEBUG
       between_will_draw_and_did_draw_(false),
 #endif
@@ -352,6 +353,7 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   layer->SetContentBounds(content_bounds());
   layer->SetContentsScale(contents_scale_x(), contents_scale_y());
   layer->SetDebugName(debug_name_);
+  layer->SetCompositingReasons(compositing_reasons_);
   layer->SetDoubleSided(double_sided_);
   layer->SetDrawCheckerboardForMissingTiles(
       draw_checkerboard_for_missing_tiles_);
@@ -1003,11 +1005,130 @@ void LayerImpl::SetVerticalScrollbarLayer(ScrollbarLayerImpl* scrollbar_layer) {
     vertical_scrollbar_layer_->set_scroll_layer_id(id());
 }
 
+scoped_ptr<base::Value>
+CompositingReasonsAsValue(WebKit::WebCompositingReasons reasons) {
+    scoped_ptr<base::ListValue> reason_list(new base::ListValue());
+
+    if (reasons == WebKit::CompositingReasonUnknown) {
+        reason_list->AppendString("No reasons given");
+        return reason_list.PassAs<base::Value>();
+    }
+
+    if (reasons & WebKit::CompositingReason3DTransform)
+        reason_list->AppendString("Has a 3d Transform");
+
+    if (reasons & WebKit::CompositingReasonVideo)
+        reason_list->AppendString("Is accelerated video");
+
+    if (reasons & WebKit::CompositingReasonCanvas)
+        reason_list->AppendString("Is accelerated canvas");
+
+    if (reasons & WebKit::CompositingReasonPlugin)
+        reason_list->AppendString("Is accelerated plugin");
+
+    if (reasons & WebKit::CompositingReasonIFrame)
+        reason_list->AppendString("Is accelerated iframe");
+
+    if (reasons & WebKit::CompositingReasonBackfaceVisibilityHidden)
+        reason_list->AppendString("Has backface-visibility: hidden");
+
+    if (reasons & WebKit::CompositingReasonAnimation)
+        reason_list->AppendString("Has accelerated animation");
+
+    if (reasons & WebKit::CompositingReasonFilters)
+        reason_list->AppendString("Has accelerated filters");
+
+    if (reasons & WebKit::CompositingReasonPositionFixed)
+        reason_list->AppendString("Is fixed position");
+
+    if (reasons & WebKit::CompositingReasonPositionSticky)
+        reason_list->AppendString("Is sticky position");
+
+    if (reasons & WebKit::CompositingReasonOverflowScrollingTouch)
+        reason_list->AppendString("Is a scrollable overflow element");
+
+    if (reasons & WebKit::CompositingReasonBlending)
+        reason_list->AppendString("Has a blend mode");
+
+    if (reasons & WebKit::CompositingReasonAssumedOverlap)
+        reason_list->AppendString("Might overlap a composited animation");
+
+    if (reasons & WebKit::CompositingReasonOverlap)
+        reason_list->AppendString("Overlaps other composited content");
+
+    if (reasons & WebKit::CompositingReasonNegativeZIndexChildren)
+        reason_list->AppendString("Might overlap negative z-index "
+                                  "composited content");
+
+    if (reasons & WebKit::CompositingReasonTransformWithCompositedDescendants)
+        reason_list->AppendString("Has a transform needed by a "
+                                  "composited descendant");
+
+    if (reasons & WebKit::CompositingReasonOpacityWithCompositedDescendants)
+        reason_list->AppendString("Has opacity needed by a composited "
+                                  "descendant");
+
+    if (reasons & WebKit::CompositingReasonMaskWithCompositedDescendants)
+        reason_list->AppendString("Has a mask needed by a composited "
+                                  "descendant");
+
+    if (reasons & WebKit::CompositingReasonReflectionWithCompositedDescendants)
+        reason_list->AppendString("Has a reflection with a composited "
+                                  "descendant");
+
+    if (reasons & WebKit::CompositingReasonFilterWithCompositedDescendants)
+        reason_list->AppendString("Is a filter effect with a composited "
+                                  "descendant");
+
+    if (reasons & WebKit::CompositingReasonBlendingWithCompositedDescendants)
+        reason_list->AppendString("Has a blend mode with a composited "
+                                  "descendant");
+
+    if (reasons & WebKit::CompositingReasonClipsCompositingDescendants)
+        reason_list->AppendString("Clips a composited descendant");
+
+    if (reasons & WebKit::CompositingReasonPerspective)
+        reason_list->AppendString("Has a perspective transform needed by a "
+                                  "composited 3d descendant");
+
+    if (reasons & WebKit::CompositingReasonPreserve3D)
+        reason_list->AppendString("Has preserves-3d style with composited "
+                                  "3d descendant");
+
+    if (reasons & WebKit::CompositingReasonReflectionOfCompositedParent)
+        reason_list->AppendString("Is the reflection of a composited layer");
+
+    if (reasons & WebKit::CompositingReasonRoot)
+        reason_list->AppendString("Is the root");
+
+    if (reasons & WebKit::CompositingReasonLayerForClip)
+        reason_list->AppendString("Convenience layer, parent of main layer to "
+                                  "clip subtree");
+
+    if (reasons & WebKit::CompositingReasonLayerForDescendantClip)
+        reason_list->AppendString("Convenience layer, child of main layer to "
+                                  "clip scrolling container");
+
+    if (reasons & WebKit::CompositingReasonLayerForScrollbar)
+        reason_list->AppendString("Convenience layer for rendering scrollbar");
+
+    if (reasons & WebKit::CompositingReasonsLayerForScrollingContainer)
+        reason_list->AppendString("Convenience layer, the scrolling container");
+
+    if (reasons & WebKit::CompositingReasonsLayerForForeground)
+        reason_list->AppendString("Convenience layer, when main layer has "
+                                  "negative z-index content");
+
+    return reason_list.PassAs<base::Value>();
+}
+
 void LayerImpl::AsValueInto(base::DictionaryValue* state) const {
   TracedValue::MakeDictIntoImplicitSnapshot(state, LayerTypeAsString(), this);
   state->SetInteger("layer_id", id());
   state->Set("bounds", MathUtil::AsValue(bounds()).release());
   state->SetInteger("draws_content", DrawsContent());
+  state->Set("compositing_reasons",
+             CompositingReasonsAsValue(compositing_reasons_).release());
 
   bool clipped;
   gfx::QuadF layer_quad = MathUtil::MapQuad(