diff --git a/libs/gui/Android.bp b/libs/gui/Android.bp
index 908eee9..d1c732b 100644
--- a/libs/gui/Android.bp
+++ b/libs/gui/Android.bp
@@ -122,6 +122,7 @@
 
     shared_libs: [
         "android.hardware.graphics.common@1.1",
+        "libbase",
         "libsync",
         "libbinder",
         "libbufferhub",
diff --git a/libs/gui/FrameTimestamps.cpp b/libs/gui/FrameTimestamps.cpp
index 85ae433..96e9a85 100644
--- a/libs/gui/FrameTimestamps.cpp
+++ b/libs/gui/FrameTimestamps.cpp
@@ -18,10 +18,10 @@
 
 #define LOG_TAG "FrameEvents"
 
+#include <android-base/stringprintf.h>
 #include <cutils/compiler.h>  // For CC_[UN]LIKELY
 #include <inttypes.h>
 #include <utils/Log.h>
-#include <utils/String8.h>
 
 #include <algorithm>
 #include <limits>
@@ -29,6 +29,7 @@
 
 namespace android {
 
+using base::StringAppendF;
 
 // ============================================================================
 // FrameEvents
@@ -86,50 +87,49 @@
     releaseFence->getSignalTime();
 }
 
-static void dumpFenceTime(String8& outString, const char* name,
-        bool pending, const FenceTime& fenceTime) {
-    outString.appendFormat("--- %s", name);
+static void dumpFenceTime(std::string& outString, const char* name, bool pending,
+                          const FenceTime& fenceTime) {
+    StringAppendF(&outString, "--- %s", name);
     nsecs_t signalTime = fenceTime.getCachedSignalTime();
     if (Fence::isValidTimestamp(signalTime)) {
-        outString.appendFormat("%" PRId64 "\n", signalTime);
+        StringAppendF(&outString, "%" PRId64 "\n", signalTime);
     } else if (pending || signalTime == Fence::SIGNAL_TIME_PENDING) {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     } else if (&fenceTime == FenceTime::NO_FENCE.get()){
-        outString.appendFormat("N/A\n");
+        outString.append("N/A\n");
     } else {
-        outString.appendFormat("Error\n");
+        outString.append("Error\n");
     }
 }
 
-void FrameEvents::dump(String8& outString) const
-{
+void FrameEvents::dump(std::string& outString) const {
     if (!valid) {
         return;
     }
 
-    outString.appendFormat("-- Frame %" PRIu64 "\n", frameNumber);
-    outString.appendFormat("--- Posted      \t%" PRId64 "\n", postedTime);
-    outString.appendFormat("--- Req. Present\t%" PRId64 "\n", requestedPresentTime);
+    StringAppendF(&outString, "-- Frame %" PRIu64 "\n", frameNumber);
+    StringAppendF(&outString, "--- Posted      \t%" PRId64 "\n", postedTime);
+    StringAppendF(&outString, "--- Req. Present\t%" PRId64 "\n", requestedPresentTime);
 
-    outString.appendFormat("--- Latched     \t");
+    outString.append("--- Latched     \t");
     if (FrameEvents::isValidTimestamp(latchTime)) {
-        outString.appendFormat("%" PRId64 "\n", latchTime);
+        StringAppendF(&outString, "%" PRId64 "\n", latchTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
-    outString.appendFormat("--- Refresh (First)\t");
+    outString.append("--- Refresh (First)\t");
     if (FrameEvents::isValidTimestamp(firstRefreshStartTime)) {
-        outString.appendFormat("%" PRId64 "\n", firstRefreshStartTime);
+        StringAppendF(&outString, "%" PRId64 "\n", firstRefreshStartTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
-    outString.appendFormat("--- Refresh (Last)\t");
+    outString.append("--- Refresh (Last)\t");
     if (FrameEvents::isValidTimestamp(lastRefreshStartTime)) {
-        outString.appendFormat("%" PRId64 "\n", lastRefreshStartTime);
+        StringAppendF(&outString, "%" PRId64 "\n", lastRefreshStartTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
     dumpFenceTime(outString, "Acquire           \t",
@@ -139,11 +139,11 @@
     dumpFenceTime(outString, "Display Present   \t",
             !addPostCompositeCalled, *displayPresentFence);
 
-    outString.appendFormat("--- DequeueReady  \t");
+    outString.append("--- DequeueReady  \t");
     if (FrameEvents::isValidTimestamp(dequeueReadyTime)) {
-        outString.appendFormat("%" PRId64 "\n", dequeueReadyTime);
+        StringAppendF(&outString, "%" PRId64 "\n", dequeueReadyTime);
     } else {
-        outString.appendFormat("Pending\n");
+        outString.append("Pending\n");
     }
 
     dumpFenceTime(outString, "Release           \t",
@@ -206,11 +206,11 @@
     return lhs.valid;
 }
 
-void FrameEventHistory::dump(String8& outString) const {
+void FrameEventHistory::dump(std::string& outString) const {
     auto earliestFrame = std::min_element(
             mFrames.begin(), mFrames.end(), &FrameNumberLessThan);
     if (!earliestFrame->valid) {
-        outString.appendFormat("-- N/A\n");
+        outString.append("-- N/A\n");
         return;
     }
     for (auto frame = earliestFrame; frame != mFrames.end(); ++frame) {
diff --git a/libs/gui/GuiConfig.cpp b/libs/gui/GuiConfig.cpp
index bc0c83c..3ec20ee 100644
--- a/libs/gui/GuiConfig.cpp
+++ b/libs/gui/GuiConfig.cpp
@@ -18,8 +18,7 @@
 
 namespace android {
 
-void appendGuiConfigString(String8& configStr)
-{
+void appendGuiConfigString(std::string& configStr) {
     static const char* config =
             " [libgui"
 #ifdef DONT_USE_FENCE_SYNC
diff --git a/libs/gui/LayerDebugInfo.cpp b/libs/gui/LayerDebugInfo.cpp
index ccde9e0..cdde9a2 100644
--- a/libs/gui/LayerDebugInfo.cpp
+++ b/libs/gui/LayerDebugInfo.cpp
@@ -16,13 +16,14 @@
 
 #include <gui/LayerDebugInfo.h>
 
+#include <android-base/stringprintf.h>
+
 #include <ui/DebugUtils.h>
 
 #include <binder/Parcel.h>
 
-#include <utils/String8.h>
-
 using namespace android;
+using android::base::StringAppendF;
 
 #define RETURN_ON_ERROR(X) do {status_t res = (X); if (res != NO_ERROR) return res;} while(false)
 
@@ -108,38 +109,37 @@
 }
 
 std::string to_string(const LayerDebugInfo& info) {
-    String8 result;
+    std::string result;
 
-    result.appendFormat("+ %s (%s)\n", info.mType.c_str(), info.mName.c_str());
+    StringAppendF(&result, "+ %s (%s)\n", info.mType.c_str(), info.mName.c_str());
     info.mTransparentRegion.dump(result, "TransparentRegion");
     info.mVisibleRegion.dump(result, "VisibleRegion");
     info.mSurfaceDamageRegion.dump(result, "SurfaceDamageRegion");
 
-    result.appendFormat("      layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), ",
-            info.mLayerStack, info.mZ, static_cast<double>(info.mX), static_cast<double>(info.mY),
-            info.mWidth, info.mHeight);
+    StringAppendF(&result, "      layerStack=%4d, z=%9d, pos=(%g,%g), size=(%4d,%4d), ",
+                  info.mLayerStack, info.mZ, static_cast<double>(info.mX),
+                  static_cast<double>(info.mY), info.mWidth, info.mHeight);
 
-    result.appendFormat("crop=%s, ", to_string(info.mCrop).c_str());
-    result.appendFormat("isOpaque=%1d, invalidate=%1d, ", info.mIsOpaque, info.mContentDirty);
-    result.appendFormat("dataspace=%s, ", dataspaceDetails(info.mDataSpace).c_str());
-    result.appendFormat("pixelformat=%s, ", decodePixelFormat(info.mPixelFormat).c_str());
-    result.appendFormat("color=(%.3f,%.3f,%.3f,%.3f), flags=0x%08x, ",
-            static_cast<double>(info.mColor.r), static_cast<double>(info.mColor.g),
-            static_cast<double>(info.mColor.b), static_cast<double>(info.mColor.a),
-            info.mFlags);
-    result.appendFormat("tr=[%.2f, %.2f][%.2f, %.2f]",
-            static_cast<double>(info.mMatrix[0][0]), static_cast<double>(info.mMatrix[0][1]),
-            static_cast<double>(info.mMatrix[1][0]), static_cast<double>(info.mMatrix[1][1]));
+    StringAppendF(&result, "crop=%s, ", to_string(info.mCrop).c_str());
+    StringAppendF(&result, "isOpaque=%1d, invalidate=%1d, ", info.mIsOpaque, info.mContentDirty);
+    StringAppendF(&result, "dataspace=%s, ", dataspaceDetails(info.mDataSpace).c_str());
+    StringAppendF(&result, "pixelformat=%s, ", decodePixelFormat(info.mPixelFormat).c_str());
+    StringAppendF(&result, "color=(%.3f,%.3f,%.3f,%.3f), flags=0x%08x, ",
+                  static_cast<double>(info.mColor.r), static_cast<double>(info.mColor.g),
+                  static_cast<double>(info.mColor.b), static_cast<double>(info.mColor.a),
+                  info.mFlags);
+    StringAppendF(&result, "tr=[%.2f, %.2f][%.2f, %.2f]", static_cast<double>(info.mMatrix[0][0]),
+                  static_cast<double>(info.mMatrix[0][1]), static_cast<double>(info.mMatrix[1][0]),
+                  static_cast<double>(info.mMatrix[1][1]));
     result.append("\n");
-    result.appendFormat("      parent=%s\n", info.mParentName.c_str());
-    result.appendFormat("      activeBuffer=[%4ux%4u:%4u,%s],",
-            info.mActiveBufferWidth, info.mActiveBufferHeight,
-            info.mActiveBufferStride,
-            decodePixelFormat(info.mActiveBufferFormat).c_str());
-    result.appendFormat(" queued-frames=%d, mRefreshPending=%d",
-            info.mNumQueuedFrames, info.mRefreshPending);
+    StringAppendF(&result, "      parent=%s\n", info.mParentName.c_str());
+    StringAppendF(&result, "      activeBuffer=[%4ux%4u:%4u,%s],", info.mActiveBufferWidth,
+                  info.mActiveBufferHeight, info.mActiveBufferStride,
+                  decodePixelFormat(info.mActiveBufferFormat).c_str());
+    StringAppendF(&result, " queued-frames=%d, mRefreshPending=%d", info.mNumQueuedFrames,
+                  info.mRefreshPending);
     result.append("\n");
-    return std::string(result.c_str());
+    return result;
 }
 
 } // android
diff --git a/libs/gui/include/gui/FrameTimestamps.h b/libs/gui/include/gui/FrameTimestamps.h
index e06e40f..df02494 100644
--- a/libs/gui/include/gui/FrameTimestamps.h
+++ b/libs/gui/include/gui/FrameTimestamps.h
@@ -30,7 +30,6 @@
 
 struct FrameEvents;
 class FrameEventHistoryDelta;
-class String8;
 
 
 // Identifiers for all the events that may be recorded or reported.
@@ -72,7 +71,7 @@
     bool hasDequeueReadyInfo() const;
 
     void checkFencesForCompletion();
-    void dump(String8& outString) const;
+    void dump(std::string& outString) const;
 
     bool valid{false};
     int connectId{0};
@@ -112,7 +111,7 @@
     FrameEvents* getFrame(uint64_t frameNumber);
     FrameEvents* getFrame(uint64_t frameNumber, size_t* iHint);
     void checkFencesForCompletion();
-    void dump(String8& outString) const;
+    void dump(std::string& outString) const;
 
     static constexpr size_t MAX_FRAME_HISTORY = 8;
 
diff --git a/libs/gui/include/gui/GuiConfig.h b/libs/gui/include/gui/GuiConfig.h
index b020ed9..7aa5432 100644
--- a/libs/gui/include/gui/GuiConfig.h
+++ b/libs/gui/include/gui/GuiConfig.h
@@ -17,12 +17,12 @@
 #ifndef ANDROID_GUI_CONFIG_H
 #define ANDROID_GUI_CONFIG_H
 
-#include <utils/String8.h>
+#include <string>
 
 namespace android {
 
 // Append the libgui configuration details to configStr.
-void appendGuiConfigString(String8& configStr);
+void appendGuiConfigString(std::string& configStr);
 
 }; // namespace android
 
diff --git a/libs/gui/tests/Android.bp b/libs/gui/tests/Android.bp
index 6de641d..f020a40 100644
--- a/libs/gui/tests/Android.bp
+++ b/libs/gui/tests/Android.bp
@@ -37,6 +37,7 @@
     shared_libs: [
         "android.hardware.configstore@1.0",
         "android.hardware.configstore-utils",
+        "libbase",
         "liblog",
         "libEGL",
         "libGLESv1_CM",
diff --git a/libs/renderengine/Android.bp b/libs/renderengine/Android.bp
index 997ae90..d872f02 100644
--- a/libs/renderengine/Android.bp
+++ b/libs/renderengine/Android.bp
@@ -18,6 +18,7 @@
         "-DEGL_EGLEXT_PROTOTYPES",
     ],
     shared_libs: [
+        "libbase",
         "libcutils",
         "libEGL",
         "libGLESv1_CM",
diff --git a/libs/renderengine/gl/GLESRenderEngine.cpp b/libs/renderengine/gl/GLESRenderEngine.cpp
index 8a9e7bd..1395551 100644
--- a/libs/renderengine/gl/GLESRenderEngine.cpp
+++ b/libs/renderengine/gl/GLESRenderEngine.cpp
@@ -27,6 +27,7 @@
 
 #include <GLES2/gl2.h>
 #include <GLES2/gl2ext.h>
+#include <android-base/stringprintf.h>
 #include <cutils/compiler.h>
 #include <renderengine/Mesh.h>
 #include <renderengine/Texture.h>
@@ -36,7 +37,6 @@
 #include <ui/Rect.h>
 #include <ui/Region.h>
 #include <utils/KeyedVector.h>
-#include <utils/String8.h>
 #include <utils/Trace.h>
 #include "GLExtensions.h"
 #include "GLFramebuffer.h"
@@ -109,6 +109,7 @@
 namespace renderengine {
 namespace gl {
 
+using base::StringAppendF;
 using ui::Dataspace;
 
 static status_t selectConfigForAttribute(EGLDisplay dpy, EGLint const* attrs, EGLint attribute,
@@ -854,22 +855,22 @@
     return mMaxViewportDims[0] < mMaxViewportDims[1] ? mMaxViewportDims[0] : mMaxViewportDims[1];
 }
 
-void GLESRenderEngine::dump(String8& result) {
+void GLESRenderEngine::dump(std::string& result) {
     const GLExtensions& extensions = GLExtensions::getInstance();
 
-    result.appendFormat("EGL implementation : %s\n", extensions.getEGLVersion());
-    result.appendFormat("%s\n", extensions.getEGLExtensions());
+    StringAppendF(&result, "EGL implementation : %s\n", extensions.getEGLVersion());
+    StringAppendF(&result, "%s\n", extensions.getEGLExtensions());
 
-    result.appendFormat("GLES: %s, %s, %s\n", extensions.getVendor(), extensions.getRenderer(),
-                        extensions.getVersion());
-    result.appendFormat("%s\n", extensions.getExtensions());
+    StringAppendF(&result, "GLES: %s, %s, %s\n", extensions.getVendor(), extensions.getRenderer(),
+                  extensions.getVersion());
+    StringAppendF(&result, "%s\n", extensions.getExtensions());
 
-    result.appendFormat("RenderEngine program cache size: %zu\n",
-                        ProgramCache::getInstance().getSize());
+    StringAppendF(&result, "RenderEngine program cache size: %zu\n",
+                  ProgramCache::getInstance().getSize());
 
-    result.appendFormat("RenderEngine last dataspace conversion: (%s) to (%s)\n",
-                        dataspaceDetails(static_cast<android_dataspace>(mDataSpace)).c_str(),
-                        dataspaceDetails(static_cast<android_dataspace>(mOutputDataSpace)).c_str());
+    StringAppendF(&result, "RenderEngine last dataspace conversion: (%s) to (%s)\n",
+                  dataspaceDetails(static_cast<android_dataspace>(mDataSpace)).c_str(),
+                  dataspaceDetails(static_cast<android_dataspace>(mOutputDataSpace)).c_str());
 }
 
 GLESRenderEngine::GlesVersion GLESRenderEngine::parseGlesVersion(const char* str) {
diff --git a/libs/renderengine/gl/GLESRenderEngine.h b/libs/renderengine/gl/GLESRenderEngine.h
index 8876d66..21d5b81 100644
--- a/libs/renderengine/gl/GLESRenderEngine.h
+++ b/libs/renderengine/gl/GLESRenderEngine.h
@@ -30,8 +30,6 @@
 
 namespace android {
 
-class String8;
-
 namespace renderengine {
 
 class Mesh;
@@ -79,7 +77,7 @@
     EGLConfig getEGLConfig() const { return mEGLConfig; }
 
 protected:
-    void dump(String8& result) override;
+    void dump(std::string& result) override;
     void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop,
                                   ui::Transform::orientation_flags rotation) override;
     void setupLayerBlending(bool premultipliedAlpha, bool opaque, bool disableTexture,
diff --git a/libs/renderengine/include/renderengine/RenderEngine.h b/libs/renderengine/include/renderengine/RenderEngine.h
index bb7f4df..8eaa2d2 100644
--- a/libs/renderengine/include/renderengine/RenderEngine.h
+++ b/libs/renderengine/include/renderengine/RenderEngine.h
@@ -39,7 +39,6 @@
 
 namespace android {
 
-class String8;
 class Rect;
 class Region;
 
@@ -76,7 +75,7 @@
     virtual void primeCache() const = 0;
 
     // dump the extension strings. always call the base class.
-    virtual void dump(String8& result) = 0;
+    virtual void dump(std::string& result) = 0;
 
     virtual bool useNativeFenceSync() const = 0;
     virtual bool useWaitSync() const = 0;
diff --git a/libs/renderengine/tests/Android.bp b/libs/renderengine/tests/Android.bp
index 65b7c82..051b8b6 100644
--- a/libs/renderengine/tests/Android.bp
+++ b/libs/renderengine/tests/Android.bp
@@ -24,6 +24,7 @@
         "librenderengine",
     ],
     shared_libs: [
+        "libbase",
         "libcutils",
         "libEGL",
         "libGLESv2",
diff --git a/libs/ui/GraphicBufferAllocator.cpp b/libs/ui/GraphicBufferAllocator.cpp
index eaba1ed..a2f1783 100644
--- a/libs/ui/GraphicBufferAllocator.cpp
+++ b/libs/ui/GraphicBufferAllocator.cpp
@@ -24,9 +24,9 @@
 
 #include <grallocusage/GrallocUsageConversion.h>
 
+#include <android-base/stringprintf.h>
 #include <log/log.h>
 #include <utils/Singleton.h>
-#include <utils/String8.h>
 #include <utils/Trace.h>
 
 #include <ui/Gralloc2.h>
@@ -35,6 +35,8 @@
 namespace android {
 // ---------------------------------------------------------------------------
 
+using base::StringAppendF;
+
 ANDROID_SINGLETON_STATIC_INSTANCE( GraphicBufferAllocator )
 
 Mutex GraphicBufferAllocator::sLock;
@@ -50,46 +52,37 @@
 
 GraphicBufferAllocator::~GraphicBufferAllocator() {}
 
-void GraphicBufferAllocator::dump(String8& result) const
-{
+void GraphicBufferAllocator::dump(std::string& result) const {
     Mutex::Autolock _l(sLock);
     KeyedVector<buffer_handle_t, alloc_rec_t>& list(sAllocList);
     size_t total = 0;
-    const size_t SIZE = 4096;
-    char buffer[SIZE];
-    snprintf(buffer, SIZE, "Allocated buffers:\n");
-    result.append(buffer);
+    result.append("Allocated buffers:\n");
     const size_t c = list.size();
     for (size_t i=0 ; i<c ; i++) {
         const alloc_rec_t& rec(list.valueAt(i));
         if (rec.size) {
-            snprintf(buffer, SIZE, "%10p: %7.2f KiB | %4u (%4u) x %4u | %4u | %8X | 0x%" PRIx64
-                    " | %s\n",
-                    list.keyAt(i), rec.size/1024.0,
-                    rec.width, rec.stride, rec.height, rec.layerCount, rec.format,
-                    rec.usage, rec.requestorName.c_str());
+            StringAppendF(&result,
+                          "%10p: %7.2f KiB | %4u (%4u) x %4u | %4u | %8X | 0x%" PRIx64 " | %s\n",
+                          list.keyAt(i), rec.size / 1024.0, rec.width, rec.stride, rec.height,
+                          rec.layerCount, rec.format, rec.usage, rec.requestorName.c_str());
         } else {
-            snprintf(buffer, SIZE, "%10p: unknown     | %4u (%4u) x %4u | %4u | %8X | 0x%" PRIx64
-                    " | %s\n",
-                    list.keyAt(i),
-                    rec.width, rec.stride, rec.height, rec.layerCount, rec.format,
-                    rec.usage, rec.requestorName.c_str());
+            StringAppendF(&result,
+                          "%10p: unknown     | %4u (%4u) x %4u | %4u | %8X | 0x%" PRIx64 " | %s\n",
+                          list.keyAt(i), rec.width, rec.stride, rec.height, rec.layerCount,
+                          rec.format, rec.usage, rec.requestorName.c_str());
         }
-        result.append(buffer);
         total += rec.size;
     }
-    snprintf(buffer, SIZE, "Total allocated (estimate): %.2f KB\n", total/1024.0);
-    result.append(buffer);
+    StringAppendF(&result, "Total allocated (estimate): %.2f KB\n", total / 1024.0);
 
-    std::string deviceDump = mAllocator->dumpDebugInfo();
-    result.append(deviceDump.c_str(), deviceDump.size());
+    result.append(mAllocator->dumpDebugInfo());
 }
 
 void GraphicBufferAllocator::dumpToSystemLog()
 {
-    String8 s;
+    std::string s;
     GraphicBufferAllocator::getInstance().dump(s);
-    ALOGD("%s", s.string());
+    ALOGD("%s", s.c_str());
 }
 
 status_t GraphicBufferAllocator::allocate(uint32_t width, uint32_t height,
diff --git a/libs/ui/Region.cpp b/libs/ui/Region.cpp
index 618c7d6..3bd3748 100644
--- a/libs/ui/Region.cpp
+++ b/libs/ui/Region.cpp
@@ -19,8 +19,9 @@
 #include <inttypes.h>
 #include <limits.h>
 
+#include <android-base/stringprintf.h>
+
 #include <utils/Log.h>
-#include <utils/String8.h>
 #include <utils/CallStack.h>
 
 #include <ui/Rect.h>
@@ -41,6 +42,8 @@
 namespace android {
 // ----------------------------------------------------------------------------
 
+using base::StringAppendF;
+
 enum {
     op_nand = region_operator<Rect>::op_nand,
     op_and  = region_operator<Rect>::op_and,
@@ -868,16 +871,14 @@
 
 // ----------------------------------------------------------------------------
 
-void Region::dump(String8& out, const char* what, uint32_t /* flags */) const
-{
+void Region::dump(std::string& out, const char* what, uint32_t /* flags */) const {
     const_iterator head = begin();
     const_iterator const tail = end();
 
-    out.appendFormat("  Region %s (this=%p, count=%" PRIdPTR ")\n",
-            what, this, tail - head);
+    StringAppendF(&out, "  Region %s (this=%p, count=%" PRIdPTR ")\n", what, this, tail - head);
     while (head != tail) {
-        out.appendFormat("    [%3d, %3d, %3d, %3d]\n", head->left, head->top,
-                head->right, head->bottom);
+        StringAppendF(&out, "    [%3d, %3d, %3d, %3d]\n", head->left, head->top, head->right,
+                      head->bottom);
         ++head;
     }
 }
diff --git a/libs/ui/UiConfig.cpp b/libs/ui/UiConfig.cpp
index 7730690..0ac863d 100644
--- a/libs/ui/UiConfig.cpp
+++ b/libs/ui/UiConfig.cpp
@@ -18,8 +18,7 @@
 
 namespace android {
 
-void appendUiConfigString(String8& configStr)
-{
+void appendUiConfigString(std::string& configStr) {
     static const char* config =
             " [libui]";
     configStr.append(config);
diff --git a/libs/ui/include/ui/GraphicBufferAllocator.h b/libs/ui/include/ui/GraphicBufferAllocator.h
index 14a865e..7e2b230 100644
--- a/libs/ui/include/ui/GraphicBufferAllocator.h
+++ b/libs/ui/include/ui/GraphicBufferAllocator.h
@@ -39,7 +39,6 @@
 }
 
 class GraphicBufferMapper;
-class String8;
 
 class GraphicBufferAllocator : public Singleton<GraphicBufferAllocator>
 {
@@ -53,7 +52,7 @@
 
     status_t free(buffer_handle_t handle);
 
-    void dump(String8& res) const;
+    void dump(std::string& res) const;
     static void dumpToSystemLog();
 
 private:
diff --git a/libs/ui/include/ui/Region.h b/libs/ui/include/ui/Region.h
index 0a09960..79642ae 100644
--- a/libs/ui/include/ui/Region.h
+++ b/libs/ui/include/ui/Region.h
@@ -27,12 +27,11 @@
 
 #include <android-base/macros.h>
 
+#include <string>
+
 namespace android {
 // ---------------------------------------------------------------------------
 
-class String8;
-
-// ---------------------------------------------------------------------------
 class Region : public LightFlattenable<Region>
 {
 public:
@@ -144,8 +143,8 @@
             status_t    flatten(void* buffer, size_t size) const;
             status_t    unflatten(void const* buffer, size_t size);
 
-    void        dump(String8& out, const char* what, uint32_t flags=0) const;
-    void        dump(const char* what, uint32_t flags=0) const;
+            void        dump(std::string& out, const char* what, uint32_t flags=0) const;
+            void        dump(const char* what, uint32_t flags=0) const;
 
 private:
     class rasterizer;
diff --git a/libs/ui/include/ui/UiConfig.h b/libs/ui/include/ui/UiConfig.h
index fcf8ed5..d1d6014 100644
--- a/libs/ui/include/ui/UiConfig.h
+++ b/libs/ui/include/ui/UiConfig.h
@@ -17,12 +17,12 @@
 #ifndef ANDROID_UI_CONFIG_H
 #define ANDROID_UI_CONFIG_H
 
-#include <utils/String8.h>
+#include <string>
 
 namespace android {
 
 // Append the libui configuration details to configStr.
-void appendUiConfigString(String8& configStr);
+void appendUiConfigString(std::string& configStr);
 
 }; // namespace android