[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 {
+const int kDumpVersion = 1;  // For tracing backwards compatibility,

[dsinclair, 2015/02/26 18:00:01]

Named keys would get rid of the need for this versioning ...

+}
+
 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 {
+  value->SetInteger("v", kDumpVersion);
+
+  value->BeginArray("vm_regions_headers");
+  value->AppendString("start_address"),
+  value->AppendString("size_in_bytes"),
+  value->AppendString("protection_flags"),
+  value->AppendString("mapped_file"),
+  value->AppendString("mapped_offset"),
+  value->AppendString("byte_stats_resident"),
+  value->AppendString("byte_stats_anonymous"),
+  value->EndArray();
+
   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->BeginDictionary("byte_stats");
-    value->SetDouble("resident", region.byte_stats_resident);
-    value->SetDouble("anonymous", region.byte_stats_anonymous);
-    value->EndDictionary();
-
-    value->EndDictionary();
+    value->BeginArray();
+    value->AppendString(StringPrintf("%" PRIx64, region.start_address));
+    value->AppendString(StringPrintf("%" PRIx64, region.size_in_bytes));
+    value->AppendInteger(region.protection_flags);
+    value->AppendString(region.mapped_file);
+    value->AppendString(StringPrintf("%" PRIx64, region.mapped_file_offset));
+    value->AppendString(StringPrintf("%" PRIx64, region.byte_stats_resident));
+    value->AppendString(StringPrintf("%" PRIx64, region.byte_stats_anonymous));
+    value->EndArray();
   }
   value->EndArray();
 }
 
 }  // namespace trace_event
 }  // namespace base