Implement SkPicture::bytesUsed() for SkRecord backend

tests/PictureTest.cpp

Index: tests/PictureTest.cpp
diff --git a/tests/PictureTest.cpp b/tests/PictureTest.cpp
index 5bc60371c997f957f56a0f122602812822c813fb..728ecedb4ba4adaeffbb094a996871f060e9614d 100644
--- a/tests/PictureTest.cpp
+++ b/tests/PictureTest.cpp
@@ -1721,6 +1721,20 @@ static void test_gen_id(skiatest::Reporter* reporter) {
     REPORTER_ASSERT(reporter, hasData->uniqueID() != empty->uniqueID());
 }
 
+static void test_bytes_used(skiatest::Reporter* reporter) {
+    SkPictureRecorder recorder;
+
+    recorder.beginRecording(0, 0);
+    SkAutoTUnref<SkPicture> empty(recorder.endRecording());
+
+    // A SkPicture also has SkRecord and possibly SkBBHierarchy as members.

[mtklein, 2014/11/17 21:43:20]

As written, there will be no BBH.  Did you want to add one?

+    REPORTER_ASSERT(reporter, SkPictureUtils::approximateBytesUsed(empty.get()) >=
+                              sizeof(SkPicture));
+
+    // Protect against any unintentional bloat.
+    REPORTER_ASSERT(reporter, SkPictureUtils::approximateBytesUsed(empty.get()) <= 176);
+}
+
 DEF_TEST(Picture, reporter) {
 #ifdef SK_DEBUG
     test_deleting_empty_picture();
@@ -1743,6 +1757,7 @@ DEF_TEST(Picture, reporter) {
     test_hierarchical(reporter);
     test_gen_id(reporter);
     test_savelayer_extraction(reporter);
+    test_bytes_used(reporter);
 }
 
 static void draw_bitmaps(const SkBitmap bitmap, SkCanvas* canvas) {
@@ -1837,6 +1852,7 @@ struct CountingBBH : public SkBBoxHierarchy {
     }
 
     virtual void insert(SkAutoTMalloc<SkRect>*, int) SK_OVERRIDE {}
+    virtual size_t bytesUsed() const { return 0; }
 };
 
 class SpoonFedBBHFactory : public SkBBHFactory {