Revert two cc patches due to crashes on canary.

Revert two cc patches due to crashes on canary.

This is a revert of two cc patches:
1) cc: Always use invalidation on the pending tree when deciding to share
  https://crrev.com/82e46120237bc023559ac7ebddb29e21b6530170
2) cc: Always keep the PictureLayerImpl::twin_layer_ pointer valid
  https://crrev.com/11f13546fd3ee3d53921c23861bf970bd2bb6428

These are being reverted together because (1) depends on (2). Landing
through the CQ to prevent too much chaos muppet.

Reason for revert:
I suspect these patches are causing canary crashers (see http://crbug.com/427215)

TBR=enne@chromium.org,vmpstr@chromium.org,danakj@chromium.org
BUG=407418, 387116, 427215
Committed: https://crrev.com/3b9478b2e834e05242772cf054730cff2491e84f
Cr-Commit-Position: refs/heads/master@{#301299}

[pdr., 2014-10-25 22:02:48]

Created Revert of cc: Always keep the PictureLayerImpl::twin_layer_ pointer
valid.

[pdr., 2014-10-25 22:06:32]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-10-25 22:07:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/680793002/1

[commit-bot: I haz the power, 2014-10-25 22:07:32]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-25 22:07:34]

Failed to apply patch for cc/layers/picture_layer_impl.cc:
While running git apply --index -3 -p1;
  error: patch failed: cc/layers/picture_layer_impl.cc:649
  error: repository lacks the necessary blob to fall back on 3-way merge.
  error: cc/layers/picture_layer_impl.cc: patch does not apply

Patch:       cc/layers/picture_layer_impl.cc
Index: cc/layers/picture_layer_impl.cc
diff --git a/cc/layers/picture_layer_impl.cc b/cc/layers/picture_layer_impl.cc
index
b088ade7a04f0c2b821699d5835cfa87c2b12f02..687243c5984f6e30ad6aaff83c680e665521a418
100644
--- a/cc/layers/picture_layer_impl.cc
+++ b/cc/layers/picture_layer_impl.cc
@@ -90,8 +90,6 @@
 }
 
 PictureLayerImpl::~PictureLayerImpl() {
-  if (twin_layer_)
-    twin_layer_->twin_layer_ = nullptr;
   layer_tree_impl()->UnregisterPictureLayerImpl(this);
 }
 
@@ -112,15 +110,10 @@
 
   LayerImpl::PushPropertiesTo(base_layer);
 
-  // Twin relationships should never change once established.
-  DCHECK_IMPLIES(twin_layer_, twin_layer_ == layer_impl);
-  DCHECK_IMPLIES(twin_layer_, layer_impl->twin_layer_ == this);
-  // The twin relationship does not need to exist before the first
-  // PushPropertiesTo from pending to active layer since before that the active
-  // layer can not have a pile or tilings, it has only been created and
inserted
-  // into the tree at that point.
-  twin_layer_ = layer_impl;
-  layer_impl->twin_layer_ = this;
+  // When the pending tree pushes to the active tree, the pending twin
+  // becomes recycled.
+  layer_impl->twin_layer_ = nullptr;
+  twin_layer_ = nullptr;
 
   layer_impl->pile_ = pile_;
 
@@ -568,16 +561,10 @@
   return visible_rect_in_content_space;
 }
 
-PictureLayerImpl* PictureLayerImpl::GetPendingOrActiveTwinLayer() const {
-  if (!twin_layer_ || !twin_layer_->IsOnActiveOrPendingTree())
-    return nullptr;
-  return twin_layer_;
-}
-
-PictureLayerImpl* PictureLayerImpl::GetRecycledTwinLayer() const {
-  if (!twin_layer_ || twin_layer_->IsOnActiveOrPendingTree())
-    return nullptr;
-  return twin_layer_;
+PictureLayerImpl* PictureLayerImpl::GetRecycledTwinLayer() {
+  // TODO(vmpstr): Maintain recycled twin as a member. crbug.com/407418
+  return static_cast<PictureLayerImpl*>(
+      layer_tree_impl()->FindRecycleTreeLayerById(id()));
 }
 
 void PictureLayerImpl::NotifyTileStateChanged(const Tile* tile) {
@@ -649,12 +636,11 @@
   return &invalidation_;
 }
 
-const PictureLayerTiling* PictureLayerImpl::GetPendingOrActiveTwinTiling(
+const PictureLayerTiling* PictureLayerImpl::GetTwinTiling(
     const PictureLayerTiling* tiling) const {
-  PictureLayerImpl* twin_layer = GetPendingOrActiveTwinLayer();
-  if (!twin_layer)
+  if (!twin_layer_)
     return nullptr;
-  return twin_layer->tilings_->TilingAtScale(tiling->contents_scale());
+  return twin_layer_->tilings_->TilingAtScale(tiling->contents_scale());
 }
 
 PictureLayerTiling* PictureLayerImpl::GetRecycledTwinTiling(
@@ -859,12 +845,16 @@
   if (!tilings_)
     tilings_ = make_scoped_ptr(new PictureLayerTilingSet(this));
 
-  PictureLayerImpl* twin_layer = GetPendingOrActiveTwinLayer();
-  if (twin_layer) {
+  DCHECK(!twin_layer_);
+  twin_layer_ = static_cast<PictureLayerImpl*>(
+      layer_tree_impl()->FindActiveTreeLayerById(id()));
+  if (twin_layer_) {
+    DCHECK(!twin_layer_->twin_layer_);
+    twin_layer_->twin_layer_ = this;
     // If the twin has never been pushed to, do not sync from it.
     // This can happen if this function is called during activation.
-    if (!twin_layer->needs_post_commit_initialization_)
-      SyncFromActiveLayer(twin_layer);
+    if (!twin_layer_->needs_post_commit_initialization_)
+      SyncFromActiveLayer(twin_layer_);
   }
 
   needs_post_commit_initialization_ = false;
@@ -878,8 +868,8 @@
 
   DCHECK(pile_->HasRecordings());
 
-  if (PictureLayerImpl* twin_layer = GetPendingOrActiveTwinLayer())
-    twin_layer->SyncTiling(tiling);
+  if (twin_layer_)
+    twin_layer_->SyncTiling(tiling);
 
   return tiling;
 }
@@ -1123,7 +1113,7 @@
       raster_contents_scale_, ideal_contents_scale_);
   float twin_low_res_scale = 0.f;
 
-  PictureLayerImpl* twin = GetPendingOrActiveTwinLayer();
+  PictureLayerImpl* twin = twin_layer_;
   if (twin && twin->CanHaveTilings()) {
     min_acceptable_high_res_scale = std::min(
         min_acceptable_high_res_scale,
@@ -1170,8 +1160,7 @@
   PictureLayerImpl* recycled_twin = GetRecycledTwinLayer();
   // Remove tilings on this tree and the twin tree.
   for (size_t i = 0; i < to_remove.size(); ++i) {
-    const PictureLayerTiling* twin_tiling =
-        GetPendingOrActiveTwinTiling(to_remove[i]);
+    const PictureLayerTiling* twin_tiling = GetTwinTiling(to_remove[i]);
     // Only remove tilings from the twin layer if they have
     // NON_IDEAL_RESOLUTION.
     if (twin_tiling && twin_tiling->resolution() == NON_IDEAL_RESOLUTION)

[commit-bot: I haz the power, 2014-10-25 22:07:45]

The CQ bit was unchecked by commit-bot@chromium.org

[pdr., 2014-10-25 22:17:36]

The CQ bit was checked by pdr@chromium.org

[commit-bot: I haz the power, 2014-10-25 22:18:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/680793002/280001

[commit-bot: I haz the power, 2014-10-26 00:12:14]

Committed patchset #2 (id:280001)

[commit-bot: I haz the power, 2014-10-26 00:13:01]

Patchset 2 (id:??) landed as
https://crrev.com/3b9478b2e834e05242772cf054730cff2491e84f
Cr-Commit-Position: refs/heads/master@{#301299}