Re-land: cc: Reduce picture cloning by creating at most one clone per raster thread.

This adds raster sequences to the TileManager. Raster tasks posted to
the same sequence are guaranteed to run in sequential order, which means
only one picture clone per sequence is required. We use the same number
of raster sequences as raster threads.

BUG=155209
TEST=manual

Review URL: https://codereview.chromium.org/11419262

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@171349 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 13 insertions, 0 deletions

diff --git a/cc/picture_pile_impl.cc b/cc/picture_pile_impl.cc
index 530a97e..f8e56cc 100644
--- a/cc/picture_pile_impl.cc
+++ b/cc/picture_pile_impl.cc
@@ -20,6 +20,19 @@ PicturePileImpl::PicturePileImpl() {
 PicturePileImpl::~PicturePileImpl() {
 }
 
+PicturePileImpl* PicturePileImpl::GetCloneForDrawingOnThread(
+    base::Thread* thread) {
+  // Do we have a clone for this thread yet?
+  CloneMap::iterator it = clones_.find(thread->thread_id());
+  if (it != clones_.end())
+    return it->second;
+
+  // Create clone for this thread.
+  scoped_refptr<PicturePileImpl> clone = CloneForDrawing();
+  clones_[thread->thread_id()] = clone;
+  return clone;
+}
+
 scoped_refptr<PicturePileImpl> PicturePileImpl::CloneForDrawing() const {
   TRACE_EVENT0("cc", "PicturePileImpl::CloneForDrawing");
   scoped_refptr<PicturePileImpl> clone = Create();