Fix up -Winconsistent-missing-override

  (and a couple presubmit fixes)

This allows us to turn back on -Werror for LLVM coverage builds,
and more generally supports building with Clang 3.7.

No public API changes.
TBR=reed@google.com

BUG=skia:

Review URL: https://codereview.chromium.org/1232463006
diff --git a/samplecode/SampleApp.cpp b/samplecode/SampleApp.cpp
index 7e90e98..a80ccd9 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -176,7 +176,7 @@
 #endif
     }
 
-    virtual void setUpBackend(SampleWindow* win, int msaaSampleCount) {
+    void setUpBackend(SampleWindow* win, int msaaSampleCount) override {
         SkASSERT(kNone_BackEndType == fBackend);
 
         fBackend = kNone_BackEndType;
@@ -250,7 +250,7 @@
         this->windowSizeChanged(win);
     }
 
-    virtual void tearDownBackend(SampleWindow *win) {
+    void tearDownBackend(SampleWindow *win) override {
 #if SK_SUPPORT_GPU
         if (fCurContext) {
             // in case we have outstanding refs to this guy (lua?)
@@ -269,8 +269,7 @@
         fBackend = kNone_BackEndType;
     }
 
-    virtual SkSurface* createSurface(SampleWindow::DeviceType dType,
-                                     SampleWindow* win) override {
+    SkSurface* createSurface(SampleWindow::DeviceType dType, SampleWindow* win) override {
 #if SK_SUPPORT_GPU
         if (IsGpuDeviceType(dType) && fCurContext) {
             SkSurfaceProps props(win->getSurfaceProps());
@@ -280,9 +279,8 @@
         return NULL;
     }
 
-    virtual void publishCanvas(SampleWindow::DeviceType dType,
-                               SkCanvas* canvas,
-                               SampleWindow* win) {
+    void publishCanvas(SampleWindow::DeviceType dType,
+                       SkCanvas* canvas, SampleWindow* win) override {
 #if SK_SUPPORT_GPU
         if (fCurContext) {
             // in case we have queued drawing calls
@@ -305,7 +303,7 @@
         win->present();
     }
 
-    virtual void windowSizeChanged(SampleWindow* win) {
+    void windowSizeChanged(SampleWindow* win) override {
 #if SK_SUPPORT_GPU
         if (fCurContext) {
             AttachmentInfo attachmentInfo;
@@ -316,7 +314,7 @@
 #endif
     }
 
-    virtual GrContext* getGrContext() {
+    GrContext* getGrContext() override {
 #if SK_SUPPORT_GPU
         return fCurContext;
 #else
diff --git a/samplecode/SampleCamera.cpp b/samplecode/SampleCamera.cpp
index 1f3b8c3..991013a 100644
--- a/samplecode/SampleCamera.cpp
+++ b/samplecode/SampleCamera.cpp
@@ -57,7 +57,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "Camera");
             return true;
@@ -65,7 +65,7 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         canvas->translate(this->width()/2, this->height()/2);
 
         Sk3DView    view;
diff --git a/samplecode/SampleFatBits.cpp b/samplecode/SampleFatBits.cpp
index 62d4a3d..9036fbe 100644
--- a/samplecode/SampleFatBits.cpp
+++ b/samplecode/SampleFatBits.cpp
@@ -446,7 +446,7 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         fFB.drawBG(canvas);
         if (fFB.getTriangle()) {
             fFB.drawTriangle(canvas, fPts);
@@ -473,8 +473,7 @@
         }
     }
 
-    virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
-                                              unsigned modi) override {
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
         SkPoint pt = { x, y };
         int index = -1;
         int count = fFB.getTriangle() ? 3 : 2;
diff --git a/samplecode/SampleLayers.cpp b/samplecode/SampleLayers.cpp
index 62a8c3b..0c34638 100644
--- a/samplecode/SampleLayers.cpp
+++ b/samplecode/SampleLayers.cpp
@@ -141,7 +141,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "Layers");
             return true;
@@ -153,7 +153,7 @@
         canvas->drawColor(SK_ColorGRAY);
     }
 
-    virtual void onDraw(SkCanvas* canvas) {
+    void onDraw(SkCanvas* canvas) override {
         this->drawBG(canvas);
 
         if (true) {
@@ -214,14 +214,13 @@
         test_fade(canvas);
     }
 
-    virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
-                                              unsigned modi) override {
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
         this->inval(NULL);
 
         return this->INHERITED::onFindClickHandler(x, y, modi);
     }
 
-    virtual bool onClick(Click* click) {
+    bool onClick(Click* click) override {
         return this->INHERITED::onClick(click);
     }
 
diff --git a/samplecode/SampleLines.cpp b/samplecode/SampleLines.cpp
index 4b491a5..0166bc0 100644
--- a/samplecode/SampleLines.cpp
+++ b/samplecode/SampleLines.cpp
@@ -34,7 +34,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "Lines");
             return true;
@@ -62,7 +62,7 @@
         canvas->drawRect(r, paint);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         SkBitmap bm;
         SkImageDecoder::DecodeFile("/kill.gif", &bm);
         canvas->drawBitmap(bm, 0, 0, NULL);
diff --git a/samplecode/SampleManyRects.cpp b/samplecode/SampleManyRects.cpp
index 5032498..a570853 100644
--- a/samplecode/SampleManyRects.cpp
+++ b/samplecode/SampleManyRects.cpp
@@ -34,7 +34,7 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         SkISize dsize = canvas->getDeviceSize();
         canvas->clear(0xFFF0E0F0);
 
diff --git a/samplecode/SamplePatch.cpp b/samplecode/SamplePatch.cpp
index ac500bf..9ada9ef 100644
--- a/samplecode/SamplePatch.cpp
+++ b/samplecode/SamplePatch.cpp
@@ -262,7 +262,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt)  {
+    bool onQuery(SkEvent* evt)  override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "Patch");
             return true;
@@ -270,7 +270,7 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         const int nu = 10;
         const int nv = 10;
 
@@ -334,8 +334,7 @@
         return SkPoint::Length(pt.fX - x, pt.fY - y) < SkIntToScalar(5);
     }
 
-    virtual SkView::Click* onFindClickHandler(SkScalar x, SkScalar y,
-                                              unsigned modi) override {
+    SkView::Click* onFindClickHandler(SkScalar x, SkScalar y, unsigned modi) override {
         x -= DX;
         y -= DY;
         for (size_t i = 0; i < SK_ARRAY_COUNT(fPts); i++) {
@@ -346,7 +345,7 @@
         return this->INHERITED::onFindClickHandler(x, y, modi);
     }
 
-    virtual bool onClick(Click* click) {
+    bool onClick(Click* click) override {
         fPts[((PtClick*)click)->fIndex].set(click->fCurr.fX - DX, click->fCurr.fY - DY);
         this->inval(NULL);
         return true;
diff --git a/samplecode/SamplePath.cpp b/samplecode/SamplePath.cpp
index 4493d39..313abca 100644
--- a/samplecode/SamplePath.cpp
+++ b/samplecode/SamplePath.cpp
@@ -142,7 +142,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "Paths");
             return true;
@@ -173,7 +173,7 @@
         canvas->drawPath(path, paint);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         this->init();
         canvas->translate(50, 50);
 
@@ -194,7 +194,7 @@
             canvas->translate(0, 200);
         }
     }
-    
+
     bool onAnimate(const SkAnimTimer& timer) override {
         SkScalar currSecs = timer.scaled(100);
         SkScalar delta = currSecs - fPrevSecs;
@@ -241,7 +241,7 @@
             fPts[i].fX = 20 + rand.nextUScalar1() * 640;
             fPts[i].fY = 20 + rand.nextUScalar1() * 480;
         }
-        
+
         const SkScalar rad = 50;
 
         fPtsPaint.setAntiAlias(true);
@@ -289,7 +289,7 @@
         }
         return this->INHERITED::onQuery(evt);
     }
-    
+
     void makePath(SkPath* path) {
         path->moveTo(fPts[0]);
         for (int i = 1; i < N; ++i) {
diff --git a/samplecode/SamplePathClip.cpp b/samplecode/SamplePathClip.cpp
index ab7ed5d..494debf 100644
--- a/samplecode/SamplePathClip.cpp
+++ b/samplecode/SamplePathClip.cpp
@@ -37,7 +37,7 @@
 
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "PathClip");
             return true;
@@ -45,7 +45,7 @@
         return this->INHERITED::onQuery(evt);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         SkRect oval = fOval;
         oval.offset(fCenter.fX - oval.centerX(), fCenter.fY - oval.centerY());
 
@@ -74,7 +74,7 @@
         return new Click(this);
     }
 
-    virtual bool onClick(Click* click) {
+    bool onClick(Click* click) override {
         fCenter.set(click->fCurr.fX, click->fCurr.fY);
         this->inval(NULL);
         return false;
diff --git a/samplecode/SamplePathFuzz.cpp b/samplecode/SamplePathFuzz.cpp
index 55f7f41..0955ce9 100644
--- a/samplecode/SamplePathFuzz.cpp
+++ b/samplecode/SamplePathFuzz.cpp
@@ -652,7 +652,7 @@
     }
 protected:
     // overrides from SkEventSink
-    virtual bool onQuery(SkEvent* evt) {
+    bool onQuery(SkEvent* evt) override {
         if (SampleCode::TitleQ(*evt)) {
             SampleCode::TitleR(evt, "PathFuzzer");
             return true;
@@ -668,7 +668,7 @@
         path_fuzz_stroker(&offscreen, fIndex);
     }
 
-    virtual void onDrawContent(SkCanvas* canvas) {
+    void onDrawContent(SkCanvas* canvas) override {
         if (fOneDraw) {
             fuzzPath.randomize();
             const SkPath& path = fuzzPath.getPath();