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

1 files changed, 2 insertions, 2 deletions

diff --git a/bench/MutexBench.cpp b/bench/MutexBench.cpp
index 8d7eb98546..2565d3860e 100644
--- a/bench/MutexBench.cpp
+++ b/bench/MutexBench.cpp
@@ -14,11 +14,11 @@ public:
     }
 
 protected:
-    virtual const char* onGetName() {
+    const char* onGetName() override {
         return "mutex";
     }
 
-    virtual void onDraw(const int loops, SkCanvas*) {
+    void onDraw(const int loops, SkCanvas*) override {
         SkMutex mu;
         for (int i = 0; i < loops; i++) {
             mu.acquire();