Revert of Refactoring: Move some classes from content/child to platform

components/test_runner/test_common.cc

Index: components/test_runner/test_common.cc
diff --git a/components/test_runner/test_common.cc b/components/test_runner/test_common.cc
index ab02077d061056cf700cea20de7f90292b74488f..2c7c772dfca37f18cf3b7e1c5f9dccdce19d0fd1 100644
--- a/components/test_runner/test_common.cc
+++ b/components/test_runner/test_common.cc
@@ -33,10 +33,6 @@ class MockBlinkPlatform : NON_EXPORTED_BASE(public blink::Platform) {
   }
   ~MockBlinkPlatform() override {}
 
-  void registerMemoryDumpProvider(blink::WebMemoryDumpProvider*,
-                                  const char* name) override {}
-  void unregisterMemoryDumpProvider(blink::WebMemoryDumpProvider*) override {}
-
  private:
   DISALLOW_COPY_AND_ASSIGN(MockBlinkPlatform);
 };