[tracing] Improve the memory maps dumper generation format.

base/trace_event/process_memory_maps.cc

 // Copyright 2015 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/process_memory_maps.h"
 
+#include "base/format_macros.h"
+#include "base/strings/stringprintf.h"
 #include "base/trace_event/trace_event_argument.h"
 
 namespace base {
 namespace trace_event {
 
 // static
 const uint32 ProcessMemoryMaps::VMRegion::kProtectionFlagsRead = 4;
 const uint32 ProcessMemoryMaps::VMRegion::kProtectionFlagsWrite = 2;
 const uint32 ProcessMemoryMaps::VMRegion::kProtectionFlagsExec = 1;
 
 ProcessMemoryMaps::ProcessMemoryMaps() {
 }
 
 ProcessMemoryMaps::~ProcessMemoryMaps() {
 }
 
 void ProcessMemoryMaps::AsValueInto(TracedValue* value) const {
+  static const char kHexFmt[] = "%" PRIx64;

[petrcermak, 2015/03/20 11:23:34]

Is there an easy way to share this constant with
base/trace_event/process_memory_totals.cc as well?

[Primiano Tucci (use gerrit), 2015/03/20 13:59:14]

Yeah I thought about that, but sharing this would be more boilerplate and less
readability than just repeating this.
The drama becomes: which header should define kHexFmt (or the entire
StringPrintf?). A new one would be overkill

+
+  // Refer to the design doc goo.gl/sxfFY8 for the semantic of these fields.
   value->BeginArray("vm_regions");
   for (const auto& region : vm_regions_) {
     value->BeginDictionary();
 
-    value->SetDouble("start_address", region.start_address);
-    value->SetDouble("size_in_bytes", region.size_in_bytes);
-    value->SetInteger("protection_flags", region.protection_flags);
-    value->SetString("mapped_file", region.mapped_file);
-    value->SetDouble("mapped_file_offset", region.mapped_file_offset);
+    value->SetString("sa", StringPrintf(kHexFmt, region.start_address));
+    value->SetString("sz", StringPrintf(kHexFmt, region.size_in_bytes));
+    value->SetInteger("pf", region.protection_flags);
+    value->SetString("mf", region.mapped_file);
 
-    value->BeginDictionary("byte_stats");
-    value->SetDouble("resident", region.byte_stats_resident);
-    value->SetDouble("anonymous", region.byte_stats_anonymous);
+    value->BeginDictionary("bs");  // byte stats
+    value->SetString(
+        "pss", StringPrintf(kHexFmt, region.byte_stats_proportional_resident));
+    value->SetString("prv",

[petrcermak, 2015/03/20 11:23:34]

nit: I'd make the coding style more consistent here by putting the line break
before "prv" and "shr" as well (like you did for "pss").

[Primiano Tucci (use gerrit), 2015/03/20 13:59:14]

I agree, but then git cl-format insists with this format, and IMHO git cl-format
should have the last word.

+                     StringPrintf(kHexFmt, region.byte_stats_private_resident));
+    value->SetString("shr",
+                     StringPrintf(kHexFmt, region.byte_stats_shared_resident));
     value->EndDictionary();
 
     value->EndDictionary();
   }
   value->EndArray();
 }
 
 }  // namespace trace_event
 }  // namespace base