Use CopyOnWriteBuffer instead of Buffer to avoid unnecessary copies.

webrtc/base/copyonwritebuffer_unittest.cc

Index: webrtc/base/copyonwritebuffer_unittest.cc
diff --git a/webrtc/base/copyonwritebuffer_unittest.cc b/webrtc/base/copyonwritebuffer_unittest.cc
index a95ad67a03e6ec2c41ad1210d3ae241f590ed3e7..769efc8c194bf75f0c66d2590e01db5a1abefcb6 100644
--- a/webrtc/base/copyonwritebuffer_unittest.cc
+++ b/webrtc/base/copyonwritebuffer_unittest.cc
@@ -41,6 +41,13 @@ void EnsureBuffersDontShareData(const CopyOnWriteBuffer& buf1,
   EXPECT_NE(data1, data2);
 }
 
+TEST(CopyOnWriteBufferTest, TestCreateEmptyData) {
+  CopyOnWriteBuffer buf(static_cast<const uint8_t*>(nullptr), 0);

[kwiberg-webrtc, 2016/03/14 11:53:49]

Do you need the static_cast here?

[joachim, 2016/03/17 20:27:21]

Yes, otherwise compilation fails with

error: no matching constructor for initialization of 'rtc::CopyOnWriteBuffer'
note: candidate constructor not viable: no known conversion from 'nullptr_t' to
'size_t' (aka 'unsigned long') for 1st argument
  CopyOnWriteBuffer(size_t size, size_t capacity);
  ^
note: candidate template ignored: could not match 'const T *' against
'nullptr_t'
  CopyOnWriteBuffer(const T* data, size_t size)
  ^

...and similar errors...

[kwiberg-webrtc, 2016/03/18 05:27:11]

Right. Thanks.

+  EXPECT_EQ(buf.size(), 0u);
+  EXPECT_EQ(buf.capacity(), 0u);
+  EXPECT_EQ(buf.data(), nullptr);
+}
+
 TEST(CopyOnWriteBufferTest, TestMoveConstruct) {
   CopyOnWriteBuffer buf1(kTestData, 3, 10);
   size_t buf1_size = buf1.size();
@@ -127,6 +134,14 @@ TEST(CopyOnWriteBufferTest, TestSetData) {
   EXPECT_EQ(buf3, CopyOnWriteBuffer(exp));
 }
 
+TEST(CopyOnWriteBufferTest, TestSetDataEmpty) {
+  CopyOnWriteBuffer buf;
+  buf.SetData(static_cast<const uint8_t*>(nullptr), 0u);

[kwiberg-webrtc, 2016/03/14 11:53:49]

...and here?

[joachim, 2016/03/17 20:27:21]

see above

[kwiberg-webrtc, 2016/03/18 05:27:11]

Acknowledged.

+  EXPECT_EQ(buf.size(), 0u);
+  EXPECT_EQ(buf.capacity(), 0u);
+  EXPECT_EQ(buf.data(), nullptr);
+}
+
 TEST(CopyOnWriteBufferTest, TestEnsureCapacity) {
   CopyOnWriteBuffer buf1(kTestData, 3, 10);
   CopyOnWriteBuffer buf2(buf1);