cc: Add trace output for individual DisplayItems

cc/resources/clip_display_item.cc

Index: cc/resources/clip_display_item.cc
diff --git a/cc/resources/clip_display_item.cc b/cc/resources/clip_display_item.cc
index 731c6059122df0930ce340ad894ad464a5242175..ec5ce94e9c30f3cf36ba7b205bc35ff154d5548d 100644
--- a/cc/resources/clip_display_item.cc
+++ b/cc/resources/clip_display_item.cc
@@ -4,7 +4,12 @@
 
 #include "cc/resources/clip_display_item.h"
 
+#include <string>
+
+#include "base/strings/stringprintf.h"
+#include "base/trace_event/trace_event_argument.h"
 #include "third_party/skia/include/core/SkCanvas.h"
+#include "ui/gfx/skia_util.h"
 
 namespace cc {
 
@@ -48,6 +53,34 @@ size_t ClipDisplayItem::PictureMemoryUsage() const {
   return total_size;
 }
 
+void ClipDisplayItem::AsValueInto(base::debug::TracedValue* array) const {
+  std::string value = base::StringPrintf("ClipDisplayItem rect: [%s]",
+                                         clip_rect_.ToString().c_str());
+  for (size_t i = 0; i < rounded_clip_rects_.size(); ++i) {

[pdr., 2015/02/02 22:22:16]

You can use a fancy c++11 iterator here to clean up the duplicated
rounded_clip_rects_[i] calls. (here, and elsewhere)

Something like:
for (auto clip_rect : rounded_clip_rects) {
 ...
}

[ajuma, 2015/02/02 23:02:21]

Done.

+    base::StringAppendF(
+        &value, " rounded_rect: [rect: [%s]",
+        gfx::SkRectToRectF(rounded_clip_rects_[i].rect()).ToString().c_str());
+    base::StringAppendF(&value, " radii: [");
+    SkVector upper_left_radius =
+        rounded_clip_rects_[i].radii(SkRRect::kUpperLeft_Corner);
+    base::StringAppendF(&value, "[%f %f]", upper_left_radius.x(),

[pdr., 2015/02/02 22:22:16]

Can you double-check that the output of these is valid json? I think we need a
comma here. (here, and elsewhere)

[ajuma, 2015/02/02 23:02:21]

Added commas.

The overall output for the list is valid json -- each item is outputting a
single string (except for DrawingDIsplayItems, which are outputting a dictionary
since they're including an SkPicture in their output), so the contents of that
string can be arbitrary. If the plan is to parse each item's string (so that
each such string should itself be valid json), then switching it to a dictionary
might be better. What works better with your tracing patch?

+                        upper_left_radius.y());
+    SkVector upper_right_radius =
+        rounded_clip_rects_[i].radii(SkRRect::kUpperRight_Corner);
+    base::StringAppendF(&value, " [%f %f]", upper_right_radius.x(),
+                        upper_right_radius.y());
+    SkVector lower_right_radius =
+        rounded_clip_rects_[i].radii(SkRRect::kLowerRight_Corner);
+    base::StringAppendF(&value, " [%f %f]", lower_right_radius.x(),
+                        lower_right_radius.y());
+    SkVector lower_left_radius =
+        rounded_clip_rects_[i].radii(SkRRect::kLowerLeft_Corner);
+    base::StringAppendF(&value, " [%f %f]]", lower_left_radius.x(),
+                        lower_left_radius.y());
+  }
+  array->AppendString(value);
+}
+
 EndClipDisplayItem::EndClipDisplayItem() {
 }
 
@@ -71,4 +104,8 @@ size_t EndClipDisplayItem::PictureMemoryUsage() const {
   return 0;
 }
 
+void EndClipDisplayItem::AsValueInto(base::debug::TracedValue* array) const {
+  array->AppendString("EndClipDisplayItem");
+}
+
 }  // namespace cc