Remove the (previosly deprecated) Pass methods

Everyone should be using std::move instead.

BUG=webrtc:5373

Review URL: https://codereview.webrtc.org/1778243006

Cr-Commit-Position: refs/heads/master@{#11962}
diff --git a/webrtc/base/buffer_unittest.cc b/webrtc/base/buffer_unittest.cc
index 80d2692..7c65447 100644
--- a/webrtc/base/buffer_unittest.cc
+++ b/webrtc/base/buffer_unittest.cc
@@ -138,7 +138,7 @@
 TEST(BufferTest, TestMoveConstruct) {
   Buffer buf1(kTestData, 3, 40);
   const uint8_t* data = buf1.data();
-  Buffer buf2(buf1.DEPRECATED_Pass());
+  Buffer buf2(std::move(buf1));
   EXPECT_EQ(buf2.size(), 3u);
   EXPECT_EQ(buf2.capacity(), 40u);
   EXPECT_EQ(buf2.data(), data);
@@ -152,7 +152,7 @@
   Buffer buf1(kTestData, 3, 40);
   const uint8_t* data = buf1.data();
   Buffer buf2(kTestData);
-  buf2 = buf1.DEPRECATED_Pass();
+  buf2 = std::move(buf1);
   EXPECT_EQ(buf2.size(), 3u);
   EXPECT_EQ(buf2.capacity(), 40u);
   EXPECT_EQ(buf2.data(), data);