Clean up dependencies for disk_cache histogram_macros.h.

net/disk_cache/backend_impl.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 "net/disk_cache/backend_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
@@ skipping 10 matching lines @@
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "net/base/net_errors.h"
 #include "net/disk_cache/cache_util.h"
 #include "net/disk_cache/disk_format.h"
 #include "net/disk_cache/entry_impl.h"
 #include "net/disk_cache/errors.h"
 #include "net/disk_cache/experiments.h"
 #include "net/disk_cache/file.h"
 
-// This has to be defined before including histogram_macros.h from this file.
-#define NET_DISK_CACHE_BACKEND_IMPL_CC_
+// Define BLOCKFILE_BACKEND_IMPL_OBJ to be a disk_cache::BackendImpl* in order

[rvargas (doing something else), 2014/02/11 19:41:48]

nit: I much prefer the original comment. It explain _why_ the include is here
rather than as part of the regular list of includes, without re-spelling what
the code already says.

The new comment "reads aloud" the code, mentions a symbol that is not evident
here (what is it, where is it, why it matters), and leaves the important part
out (this define is needed for the header that follows).

+// to use the CACHE_UMA histogram macro.
+#define BLOCKFILE_BACKEND_IMPL_OBJ this
 #include "net/disk_cache/histogram_macros.h"
 
 using base::Time;
 using base::TimeDelta;
 using base::TimeTicks;
 
 namespace {
 
 const char* kIndexName = "index";
 
@@ skipping 2048 matching lines @@
     if (total_memory > kMaxBuffersSize || total_memory <= 0)
       total_memory = kMaxBuffersSize;
 
     done = true;
   }
 
   return static_cast<int>(total_memory);
 }
 
 }  // namespace disk_cache