[SurfaceFlinger] Replace NULL with nullptr.

Test: make
Change-Id: Ia0ecb3160cd5fddf22fb7100c1759d62e723d0b7
diff --git a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
index 4186b7a..eaa5455 100644
--- a/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
+++ b/services/surfaceflinger/DisplayHardware/FramebufferSurface.h
@@ -80,7 +80,7 @@
     // on/off.
     android_dataspace mDataSpace;
 
-    // mCurrentBuffer is the current buffer or NULL to indicate that there is
+    // mCurrentBuffer is the current buffer or nullptr to indicate that there is
     // no current buffer.
     sp<GraphicBuffer> mCurrentBuffer;
 
diff --git a/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h b/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
index 4bc63bb..fe7944f 100644
--- a/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
+++ b/services/surfaceflinger/DisplayHardware/HWComposer_hwc1.h
@@ -190,7 +190,7 @@
         virtual status_t setLayer(size_t index) = 0;
         virtual HWCLayer* dup() = 0;
         static HWCLayer* copy(HWCLayer *rhs) {
-            return rhs ? rhs->dup() : NULL;
+            return rhs ? rhs->dup() : nullptr;
         }
     protected:
         virtual ~HWCLayer() { }
@@ -205,7 +205,7 @@
         HWCLayer* const mLayerList;
         size_t mIndex;
 
-        LayerListIterator() : mLayerList(NULL), mIndex(0) { }
+        LayerListIterator() : mLayerList(nullptr), mIndex(0) { }
 
         LayerListIterator(HWCLayer* layer, size_t index)
             : mLayerList(layer), mIndex(index) { }
@@ -371,8 +371,8 @@
     sp<SurfaceFlinger>              mFlinger;
     framebuffer_device_t*           mFbDev;
     struct hwc_composer_device_1*   mHwc;
-    // invariant: mLists[0] != NULL iff mHwc != NULL
-    // mLists[i>0] can be NULL. that display is to be ignored
+    // invariant: mLists[0] != nullptr iff mHwc != nullptr
+    // mLists[i>0] can be nullptr. that display is to be ignored
     struct hwc_display_contents_1*  mLists[MAX_HWC_DISPLAYS];
     DisplayData                     mDisplayData[MAX_HWC_DISPLAYS];
     // protect mDisplayData from races between prepare and dump
diff --git a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
index cde96e4..3480b24 100644
--- a/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
+++ b/services/surfaceflinger/DisplayHardware/VirtualDisplaySurface.cpp
@@ -108,7 +108,7 @@
     mConsumer->setDefaultBufferSize(sinkWidth, sinkHeight);
     sink->setAsyncMode(true);
     IGraphicBufferProducer::QueueBufferOutput output;
-    mSource[SOURCE_SCRATCH]->connect(NULL, NATIVE_WINDOW_API_EGL, false, &output);
+    mSource[SOURCE_SCRATCH]->connect(nullptr, NATIVE_WINDOW_API_EGL, false, &output);
 }
 
 VirtualDisplaySurface::~VirtualDisplaySurface() {
@@ -203,7 +203,7 @@
     }
 
     sp<GraphicBuffer> fbBuffer = mFbProducerSlot >= 0 ?
-            mProducerBuffers[mFbProducerSlot] : sp<GraphicBuffer>(NULL);
+            mProducerBuffers[mFbProducerSlot] : sp<GraphicBuffer>(nullptr);
     sp<GraphicBuffer> outBuffer = mProducerBuffers[mOutputProducerSlot];
     VDS_LOGV("advanceFrame: fb=%d(%p) out=%d(%p)",
             mFbProducerSlot, fbBuffer.get(),
@@ -214,7 +214,7 @@
     mHwc.setOutputBuffer(mDisplayId, mOutputFence, outBuffer);
 
     status_t result = NO_ERROR;
-    if (fbBuffer != NULL) {
+    if (fbBuffer != nullptr) {
         uint32_t hwcSlot = 0;
         sp<GraphicBuffer> hwcBuffer;
         mHwcBufferCache.getHwcBuffer(mFbProducerSlot, fbBuffer,