[tracing] Simplify design of MemoryAllocatorDump

base/trace_event/memory_dump_manager_unittest.cc

Index: base/trace_event/memory_dump_manager_unittest.cc
diff --git a/base/trace_event/memory_dump_manager_unittest.cc b/base/trace_event/memory_dump_manager_unittest.cc
index 638ae7db691495955d384591f93f11b7d7cc4e33..0de60b292eb24c0157cd33661a6a67eb40c94727 100644
--- a/base/trace_event/memory_dump_manager_unittest.cc
+++ b/base/trace_event/memory_dump_manager_unittest.cc
@@ -80,8 +80,16 @@ class MemoryDumpManagerTest : public testing::Test {
 class MockDumpProvider : public MemoryDumpProvider {
  public:
   MockDumpProvider() {}
-  MockDumpProvider(const scoped_refptr<SingleThreadTaskRunner>& task_runner)
+
+  explicit MockDumpProvider(
+      const scoped_refptr<SingleThreadTaskRunner>& task_runner)
       : MemoryDumpProvider(task_runner) {}
+
+  // Ctor for the SharedSessionState test.
+  explicit MockDumpProvider(const std::string& id) {
+    DeclareAllocatorAttribute("allocator" + id, "attr" + id, "type" + id);
+  }
+
   MOCK_METHOD1(DumpInto, bool(ProcessMemoryDump* pmd));
 
   // DumpInto() override for the ActiveDumpProviderConsistency test.
@@ -98,6 +106,16 @@ class MockDumpProvider : public MemoryDumpProvider {
     return true;
   }
 
+  // DumpInto() override for the SharedSessionState test.
+  bool DumpIntoAndCheckSessionState(ProcessMemoryDump* pmd) {
+    EXPECT_TRUE(pmd->session_state());
+    const auto& attrs_type_info =
+        pmd->session_state()->allocators_attributes_type_info;
+    EXPECT_TRUE(attrs_type_info.Exists("allocator1", "attr1"));
+    EXPECT_TRUE(attrs_type_info.Exists("allocator2", "attr2"));
+    return true;
+  }
+
   const char* GetFriendlyName() const override { return "MockDumpProvider"; }
 };
 
@@ -128,6 +146,24 @@ TEST_F(MemoryDumpManagerTest, SingleDumper) {
   TraceLog::GetInstance()->SetDisabled();
 }
 
+TEST_F(MemoryDumpManagerTest, SharedSessionState) {
+  MockDumpProvider mdp1("1");  // Will declare an allocator property "attr1".
+  MockDumpProvider mdp2("2");  // Will declare an allocator property "attr2".
+  mdm_->RegisterDumpProvider(&mdp1);
+  mdm_->RegisterDumpProvider(&mdp2);
+
+  EnableTracing(kTraceCategory);
+  EXPECT_CALL(mdp1, DumpInto(_)).Times(2).WillRepeatedly(
+      Invoke(&mdp1, &MockDumpProvider::DumpIntoAndCheckSessionState));
+  EXPECT_CALL(mdp2, DumpInto(_)).Times(2).WillRepeatedly(
+      Invoke(&mdp2, &MockDumpProvider::DumpIntoAndCheckSessionState));
+
+  for (int i = 0; i < 2; ++i)
+    mdm_->RequestGlobalDump(MemoryDumpType::EXPLICITLY_TRIGGERED);
+
+  DisableTracing();
+}
+
 TEST_F(MemoryDumpManagerTest, MultipleDumpers) {
   MockDumpProvider mdp1;
   MockDumpProvider mdp2;