base: Use std::move() instead of Pass() for real movable types.

base/trace_event/trace_event_argument.cc

 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/trace_event/trace_event_argument.h"
 
+#include <utility>
+
 #include "base/bits.h"
 #include "base/json/json_writer.h"
 #include "base/trace_event/trace_event_memory_overhead.h"
 #include "base/values.h"
 
 namespace base {
 namespace trace_event {
 
 namespace {
 const char kTypeStartDict = '{';
@@ skipping 415 matching lines @@
         } else {
           cur_list->AppendString(value);
         }
       } break;
 
       default:
         NOTREACHED();
     }
   }
   DCHECK(stack.empty());
-  return root.Pass();
+  return std::move(root);
 }
 
 void TracedValue::AppendAsTraceFormat(std::string* out) const {
   DCHECK_CURRENT_CONTAINER_IS(kStackTypeDict);
   DCHECK_CONTAINER_STACK_DEPTH_EQ(1u);
 
   // TODO(primiano): this could be smarter, skip the ToBaseValue encoding and
   // produce the JSON on its own. This will require refactoring JSONWriter
   // to decouple the base::Value traversal from the JSON writing bits
   std::string tmp;
   JSONWriter::Write(*ToBaseValue(), &tmp);
   *out += tmp;
 }
 
 void TracedValue::EstimateTraceMemoryOverhead(
     TraceEventMemoryOverhead* overhead) {
   const size_t kPickleHeapAlign = 4096;  // Must be == Pickle::kPickleHeapAlign.
   overhead->Add("TracedValue",
 
                 /* allocated size */
                 bits::Align(pickle_.GetTotalAllocatedSize(), kPickleHeapAlign),
 
                 /* resident size */
                 bits::Align(pickle_.size(), kPickleHeapAlign));
 }
 
 }  // namespace trace_event
 }  // namespace base