Fix crash in InvokeOnMemoryDump when tracing

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>

[Primiano Tucci (use gerrit), 2017/03/15 15:18:14]

nit: IWYU (include what you use)
can you add #include <unordered_set> here?

 
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/process/process_metrics.h"
+#include "base/trace_event/memory_dump_manager.h"
 #include "base/trace_event/process_memory_dump.h"
 #include "base/trace_event/process_memory_maps.h"
 #include "base/trace_event/process_memory_totals.h"
 #include "base/trace_event/trace_event_argument.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(OS_MACOSX)
 #include <libgen.h>
 #include <mach-o/dyld.h>
 #endif
@@ skipping 362 matching lines @@
             });
   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)
 
+class MockMemoryDumpProvider : public ProcessMetricsMemoryDumpProvider {
+ public:
+  MockMemoryDumpProvider(base::ProcessId process);
+  ~MockMemoryDumpProvider() override;
+};
+
+std::unordered_set<MockMemoryDumpProvider*> g_live_mocks;
+std::unordered_set<MockMemoryDumpProvider*> g_dead_mocks;
+
+MockMemoryDumpProvider::MockMemoryDumpProvider(base::ProcessId process)
+    : ProcessMetricsMemoryDumpProvider(process) {
+  g_live_mocks.insert(this);
+}
+
+MockMemoryDumpProvider::~MockMemoryDumpProvider() {
+  g_live_mocks.erase(this);
+  g_dead_mocks.insert(this);
+}
+
+TEST(ProcessMetricsMemoryDumpProviderTest, DoubleRegister) {
+  auto factory = [](base::ProcessId process) {
+    return std::unique_ptr<ProcessMetricsMemoryDumpProvider>(
+        new MockMemoryDumpProvider(process));
+  };
+  ProcessMetricsMemoryDumpProvider::factory_for_testing = factory;
+  ProcessMetricsMemoryDumpProvider::RegisterForProcess(1);
+  ProcessMetricsMemoryDumpProvider::RegisterForProcess(1);
+  ASSERT_EQ(1u, g_live_mocks.size());
+  ASSERT_EQ(1u, g_dead_mocks.size());
+  auto* manager = base::trace_event::MemoryDumpManager::GetInstance();
+  MockMemoryDumpProvider* live_mock = *g_live_mocks.begin();
+  EXPECT_TRUE(manager->IsDumpProviderRegisteredForTesting(live_mock));
+  auto* dead_mock = *g_dead_mocks.begin();
+  EXPECT_FALSE(manager->IsDumpProviderRegisteredForTesting(dead_mock));
+  ProcessMetricsMemoryDumpProvider::UnregisterForProcess(1);
+  g_live_mocks.clear();
+  g_dead_mocks.clear();
+}
+
 }  // namespace tracing