diff --git a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
index d0cf1b7..35f30d7 100644
--- a/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
+++ b/services/surfaceflinger/tests/unittests/SchedulerTest.cpp
@@ -117,7 +117,7 @@
             mScheduler->hotplugReceived(nullptr, EventThread::DisplayType::Primary, false));
     ASSERT_NO_FATAL_FAILURE(mScheduler->onScreenAcquired(nullptr));
     ASSERT_NO_FATAL_FAILURE(mScheduler->onScreenReleased(nullptr));
-    String8 testString;
+    std::string testString;
     ASSERT_NO_FATAL_FAILURE(mScheduler->dump(nullptr, testString));
     EXPECT_TRUE(testString == "");
     ASSERT_NO_FATAL_FAILURE(mScheduler->setPhaseOffset(nullptr, 10));
@@ -146,7 +146,7 @@
     EXPECT_CALL(*mEventThread, onScreenReleased()).Times(0);
     ASSERT_NO_FATAL_FAILURE(mScheduler->onScreenReleased(connectionHandle));
 
-    String8 testString;
+    std::string testString;
     EXPECT_CALL(*mEventThread, dump(_)).Times(0);
     ASSERT_NO_FATAL_FAILURE(mScheduler->dump(connectionHandle, testString));
     EXPECT_TRUE(testString == "");
@@ -176,7 +176,7 @@
     EXPECT_CALL(*mEventThread, onScreenReleased()).Times(1);
     ASSERT_NO_FATAL_FAILURE(mScheduler->onScreenReleased(mConnectionHandle));
 
-    String8 testString("dump");
+    std::string testString("dump");
     EXPECT_CALL(*mEventThread, dump(testString)).Times(1);
     ASSERT_NO_FATAL_FAILURE(mScheduler->dump(mConnectionHandle, testString));
     EXPECT_TRUE(testString != "");
diff --git a/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp b/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
index 186ed79..bfd34cd 100644
--- a/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
+++ b/services/surfaceflinger/tests/unittests/TimeStatsTest.cpp
@@ -21,7 +21,6 @@
 
 #include <log/log.h>
 #include <utils/String16.h>
-#include <utils/String8.h>
 #include <utils/Vector.h>
 
 #include <random>
@@ -131,7 +130,7 @@
 
 std::string TimeStatsTest::inputCommand(InputCommand cmd, bool useProto) {
     size_t index = 0;
-    String8 result;
+    std::string result;
     Vector<String16> args;
 
     switch (cmd) {
@@ -162,7 +161,7 @@
     }
 
     EXPECT_NO_FATAL_FAILURE(mTimeStats->parseArgs(useProto, args, index, result));
-    return std::string(result.string(), result.size());
+    return result;
 }
 
 static std::string genLayerName(int32_t layerID) {
diff --git a/services/surfaceflinger/tests/unittests/mock/MockDispSync.h b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
index 34e71cb..9213ae5 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockDispSync.h
@@ -18,7 +18,6 @@
 
 #include <gmock/gmock.h>
 
-#include <utils/String8.h>
 #include "Scheduler/DispSync.h"
 
 namespace android {
@@ -44,7 +43,7 @@
     MOCK_METHOD1(setIgnorePresentFences, void(bool));
     MOCK_METHOD0(expectedPresentTime, nsecs_t());
 
-    MOCK_CONST_METHOD1(dump, void(String8&));
+    MOCK_CONST_METHOD1(dump, void(std::string&));
 };
 
 } // namespace mock
diff --git a/services/surfaceflinger/tests/unittests/mock/MockEventThread.h b/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
index ad2463d..0a1c827 100644
--- a/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
+++ b/services/surfaceflinger/tests/unittests/mock/MockEventThread.h
@@ -32,7 +32,7 @@
     MOCK_METHOD0(onScreenReleased, void());
     MOCK_METHOD0(onScreenAcquired, void());
     MOCK_METHOD2(onHotplugReceived, void(DisplayType, bool));
-    MOCK_CONST_METHOD1(dump, void(String8&));
+    MOCK_CONST_METHOD1(dump, void(std::string&));
     MOCK_METHOD1(setPhaseOffset, void(nsecs_t phaseOffset));
 };
 
diff --git a/services/surfaceflinger/tests/unittests/mock/RenderEngine/MockRenderEngine.h b/services/surfaceflinger/tests/unittests/mock/RenderEngine/MockRenderEngine.h
index a416808..11e5631 100644
--- a/services/surfaceflinger/tests/unittests/mock/RenderEngine/MockRenderEngine.h
+++ b/services/surfaceflinger/tests/unittests/mock/RenderEngine/MockRenderEngine.h
@@ -38,7 +38,7 @@
     MOCK_METHOD0(createFramebuffer, std::unique_ptr<Framebuffer>());
     MOCK_METHOD0(createImage, std::unique_ptr<renderengine::Image>());
     MOCK_CONST_METHOD0(primeCache, void());
-    MOCK_METHOD1(dump, void(String8&));
+    MOCK_METHOD1(dump, void(std::string&));
     MOCK_CONST_METHOD0(useNativeFenceSync, bool());
     MOCK_CONST_METHOD0(useWaitSync, bool());
     MOCK_CONST_METHOD0(isCurrent, bool());