Update logic for emitting region information from dyld.

components/tracing/common/process_metrics_memory_dump_provider_unittest.cc

Index: components/tracing/common/process_metrics_memory_dump_provider_unittest.cc
diff --git a/components/tracing/common/process_metrics_memory_dump_provider_unittest.cc b/components/tracing/common/process_metrics_memory_dump_provider_unittest.cc
index 4c9ba7c9ac0fa86c5d2fb6d206d5f03f8f736530..d05c3a736217d93e93bf179b66b25db8389f6261 100644
--- a/components/tracing/common/process_metrics_memory_dump_provider_unittest.cc
+++ b/components/tracing/common/process_metrics_memory_dump_provider_unittest.cc
@@ -313,6 +313,30 @@ TEST(ProcessMetricsMemoryDumpProviderTest, TestMachOReading) {
   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