Update logic for emitting region information from dyld.

components/tracing/common/process_metrics_memory_dump_provider_unittest.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 "components/tracing/common/process_metrics_memory_dump_provider.h"
 
 #include <stdint.h>
 
 #include <memory>
 
@@ skipping 295 matching lines @@
           region.byte_stats_shared_clean_resident;
     }
 
     if (region.mapped_file.find("AppKit") != std::string::npos) {
       found_appkit = true;
     }
   }
   EXPECT_GT(components_unittests_resident_pages, 0u);
   EXPECT_TRUE(found_appkit);
 }
+
+TEST(ProcessMetricsMemoryDumpProviderTest, NoDuplicateRegions) {
+  using VMRegion = base::trace_event::ProcessMemoryMaps::VMRegion;
+  ProcessMetricsMemoryDumpProvider mdp(base::kNullProcessId);
+  base::trace_event::MemoryDumpArgs args;
+  base::trace_event::ProcessMemoryDump dump(nullptr, args);
+  ASSERT_TRUE(mdp.DumpProcessMemoryMaps(args, &dump));
+  ASSERT_TRUE(dump.has_process_mmaps());
+
+  std::vector<VMRegion> regions;
+  regions.reserve(dump.process_mmaps()->vm_regions().size());
+  for (const VMRegion& region : dump.process_mmaps()->vm_regions())
+    regions.push_back(region);
+  std::sort(regions.begin(), regions.end(),
+            [](const VMRegion& a, const VMRegion& b) -> bool {
+              return a.start_address < b.start_address;
+            });
+  uint64_t last_address = 0;
+  for (const VMRegion& region : regions) {
+    EXPECT_GE(region.start_address, last_address);
+    last_address = region.start_address + region.size_in_bytes;
+  }
+}
+
 #endif  // defined(OS_MACOSX)
 
 }  // namespace tracing