Add protobuf serialization to DisplayItemList

cc/playback/clip_path_display_item.cc

Index: cc/playback/clip_path_display_item.cc
diff --git a/cc/playback/clip_path_display_item.cc b/cc/playback/clip_path_display_item.cc
index 9ac5bdea80a6be6239267c57b9e27d127987927a..5494664521f70ef7760b020d433e29e70cdb7835 100644
--- a/cc/playback/clip_path_display_item.cc
+++ b/cc/playback/clip_path_display_item.cc
@@ -6,6 +6,8 @@
 
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event_argument.h"
+#include "cc/proto/display_item.pb.h"
+#include "cc/proto/skia_conversions.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace cc {
@@ -29,6 +31,38 @@ void ClipPathDisplayItem::SetNew(const SkPath& clip_path,
                       0 /* external_memory_usage */);
 }
 
+void ClipPathDisplayItem::ToProtobuf(proto::DisplayItem* proto) {
+  proto->set_type(proto::DisplayItem::Type_ClipPath);
+
+  proto::ClipPathDisplayItem* details = proto->mutable_details_clip_path();
+  details->set_clip_op(SkRegionOpToProto(clip_op_));
+  details->set_antialias(antialias_);
+
+  // Just use skia's serialization method for the SkPath for now.
+  size_t path_size = clip_path_.writeToMemory(nullptr);
+  if (path_size > 0) {
+    scoped_ptr<char[]> buffer(new char[path_size]);
+    clip_path_.writeToMemory(buffer.get());
+    details->set_clip_path(buffer.get(), path_size);

[vmpstr, 2015/10/26 17:46:17]

What's the parameter to set_clip_path? Is this a copy? It's weird to just pass a
raw ptr to a scoped_ptr thing that is deleted immediately.

Can you make it std::string(buffer.get()) to make it explicit?

[David Trainor- moved to gerrit, 2015/10/26 20:42:56]

I believe protobufs always copy the data passed in so they're self-contained
objects.  I can cast it to a string if you'd prefer that though.  It'll just do
the copy to the string constructor then ref the data internally in the protobuf.

+  }
+}
+
+void ClipPathDisplayItem::FromProtobuf(const proto::DisplayItem& proto) {
+  DCHECK_EQ(proto::DisplayItem::Type_ClipPath, proto.type());
+
+  const proto::ClipPathDisplayItem& details = proto.details_clip_path();
+  SkRegion::Op clip_op = SkRegionOpFromProto(details.clip_op());
+  bool antialias = details.antialias();
+
+  SkPath clip_path;
+  if (details.has_clip_path()) {
+    clip_path.readFromMemory(details.clip_path().c_str(),

[vmpstr, 2015/10/26 17:46:17]

Does readFromMemory return some sort of a status code? If so, can you dcheck
that it succeeded?

[David Trainor- moved to gerrit, 2015/10/26 20:42:56]

It returns the bytes read to build the SkPath.  I can DCHECK that it's the same
as the size I'm passing in.

+                             details.clip_path().size());
+  }
+
+  SetNew(clip_path, clip_op, antialias);
+}
+
 void ClipPathDisplayItem::Raster(SkCanvas* canvas,
                                  const gfx::Rect& canvas_target_playback_rect,
                                  SkPicture::AbortCallback* callback) const {
@@ -55,6 +89,14 @@ EndClipPathDisplayItem::EndClipPathDisplayItem() {
 EndClipPathDisplayItem::~EndClipPathDisplayItem() {
 }
 
+void EndClipPathDisplayItem::ToProtobuf(proto::DisplayItem* proto) {
+  proto->set_type(proto::DisplayItem::Type_EndClipPath);
+}
+
+void EndClipPathDisplayItem::FromProtobuf(const proto::DisplayItem& proto) {
+  DCHECK_EQ(proto::DisplayItem::Type_EndClipPath, proto.type());
+}
+
 void EndClipPathDisplayItem::Raster(
     SkCanvas* canvas,
     const gfx::Rect& canvas_target_playback_rect,