Replace NULL with nullptr in all C++ files.

webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc

Index: webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc
diff --git a/webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc b/webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc
index 983d05dca19b542fbcf42c044582e2069bee9ddf..1b19030919dd07c158aaab8578314b0377ea1533 100644
--- a/webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc
+++ b/webrtc/modules/audio_processing/transient/wpd_tree_unittest.cc
@@ -43,22 +43,22 @@ TEST(WPDTreeTest, Construction) {
   for (int level = 0; level <= kLevels; ++level) {
     nodes_at_level = 1 << level;
     for (int i = 0; i < nodes_at_level; ++i) {
-      ASSERT_TRUE(NULL != tree.NodeAt(level, i));
+      ASSERT_TRUE(nullptr != tree.NodeAt(level, i));
     }
     // Out of bounds.
-    EXPECT_EQ(NULL, tree.NodeAt(level, -1));
-    EXPECT_EQ(NULL, tree.NodeAt(level, -12));
-    EXPECT_EQ(NULL, tree.NodeAt(level, nodes_at_level));
-    EXPECT_EQ(NULL, tree.NodeAt(level, nodes_at_level + 5));
+    EXPECT_EQ(nullptr, tree.NodeAt(level, -1));
+    EXPECT_EQ(nullptr, tree.NodeAt(level, -12));
+    EXPECT_EQ(nullptr, tree.NodeAt(level, nodes_at_level));
+    EXPECT_EQ(nullptr, tree.NodeAt(level, nodes_at_level + 5));
   }
   // Out of bounds.
-  EXPECT_EQ(NULL, tree.NodeAt(-1, 0));
-  EXPECT_EQ(NULL, tree.NodeAt(-12, 0));
-  EXPECT_EQ(NULL, tree.NodeAt(kLevels + 1, 0));
-  EXPECT_EQ(NULL, tree.NodeAt(kLevels + 5, 0));
+  EXPECT_EQ(nullptr, tree.NodeAt(-1, 0));
+  EXPECT_EQ(nullptr, tree.NodeAt(-12, 0));
+  EXPECT_EQ(nullptr, tree.NodeAt(kLevels + 1, 0));
+  EXPECT_EQ(nullptr, tree.NodeAt(kLevels + 5, 0));
   // Checks for Update().
   EXPECT_EQ(0, tree.Update(test_buffer, kTestBufferSize));
-  EXPECT_EQ(-1, tree.Update(NULL, kTestBufferSize));
+  EXPECT_EQ(-1, tree.Update(nullptr, kTestBufferSize));
   EXPECT_EQ(-1, tree.Update(test_buffer, kTestBufferSize - 1));
 }