[Tracing] Disable registration of regular dump providers during tests

content/browser/tracing/memory_tracing_browsertest.cc

Index: content/browser/tracing/memory_tracing_browsertest.cc
diff --git a/content/browser/tracing/memory_tracing_browsertest.cc b/content/browser/tracing/memory_tracing_browsertest.cc
index 3b72e90da6f06bebe17193a23d2a2567689007b2..078e54c626c0eb106680313033dbd1bd631020d4 100644
--- a/content/browser/tracing/memory_tracing_browsertest.cc
+++ b/content/browser/tracing/memory_tracing_browsertest.cc
@@ -68,10 +68,12 @@ class MemoryTracingTest : public ContentBrowserTest {
     callback_call_count_ = 0;
     last_callback_dump_guid_ = 0;
     last_callback_success_ = false;
-    MemoryDumpManager::GetInstance()->Initialize();
     mock_dump_provider_.reset(new MockDumpProvider());
     MemoryDumpManager::GetInstance()->RegisterDumpProvider(
         mock_dump_provider_.get());
+    MemoryDumpManager::GetInstance()->set_ignore_registrations_for_testing(
+        true);
+    MemoryDumpManager::GetInstance()->Initialize();
     // TODO(primiano): This should be done via TraceConfig.
     // See https://goo.gl/5Hj3o0.
     MemoryDumpManager::GetInstance()->DisablePeriodicDumpsForTesting();