teach dump_record to recurse into subpictures

tools/DumpRecord.cpp

Index: tools/DumpRecord.cpp
diff --git a/tools/DumpRecord.cpp b/tools/DumpRecord.cpp
index e2662e758c96569206a4f4b56c9f34613c063f7e..e7d76f05155fe8ef6cff396b38a7fadceabb8403 100644
--- a/tools/DumpRecord.cpp
+++ b/tools/DumpRecord.cpp
@@ -60,6 +60,21 @@ public:
         ++fIndent;
     }
 
+    void print(const SkRecords::DrawPicture& command, double ns) {
+        this->printNameAndTime(command, ns);
+
+        if (auto bp = command.picture->asSkBigPicture()) {
+            ++fIndent;
+
+            const SkRecord& record = *bp->record();
+            for (int i = 0; i < record.count(); i++) {
+                record.visit<void>(i, *this);
+            }
+
+            --fIndent;
+        }
+    }
+
 private:
     template <typename T>
     void printNameAndTime(const T& command, double ns) {