Rearrange SkRecord public API to fit better with cc/resources/picture

src/record/SkRecorder.cpp

Index: src/record/SkRecorder.cpp
diff --git a/src/record/SkRecorder.cpp b/src/record/SkRecorder.cpp
index 345597c5bb5300e49db15d659762aef6d18236b4..fe4f35f54b1aa77372506ef86fc692a252cb95a8 100644
--- a/src/record/SkRecorder.cpp
+++ b/src/record/SkRecorder.cpp
@@ -12,6 +12,10 @@
 SkRecorder::SkRecorder(SkRecorder::Mode mode, SkRecord* record, int width, int height)
     : SkCanvas(width, height), fMode(mode), fRecord(record) {}
 
+void SkRecorder::forgetRecord() {
+    fRecord = NULL;
+}
+
 // To make appending to fRecord a little less verbose.
 #define APPEND(T, ...) \
         SkNEW_PLACEMENT_ARGS(fRecord->append<SkRecords::T>(), SkRecords::T, (__VA_ARGS__))