base: Fix an inefficiency in base::Pickle that caused extraneous allocations.

base/pickle_unittest.cc

 // Copyright (c) 2012 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 <string>
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/pickle.h"
 #include "base/strings/string16.h"
@@ skipping 410 matching lines @@
 
   PickleIterator iter(pickle);
   const char* outdata_char = NULL;
   EXPECT_TRUE(iter.ReadBytes(&outdata_char, sizeof(data)));
 
   int outdata;
   memcpy(&outdata, outdata_char, sizeof(outdata));
   EXPECT_EQ(data, outdata);
 }
 
+// Checks that when a pickle is deep-copied, the result is not larger than
+// needed.
+TEST(PickleTest, DeepCopyResize) {
+  Pickle pickle;
+  while (pickle.capacity_after_header() != pickle.payload_size())
+    pickle.WriteBool(true);
+
+  // Make a deep copy.
+  Pickle pickle2(pickle);
+
+  // Check that there isn't any extraneous capacity.
+  EXPECT_EQ(pickle.capacity_after_header(), pickle2.capacity_after_header());
+}
+
 }  // namespace base