Update {virtual,override} to follow C++11 style in content.

content/child/blink_platform_impl_unittest.cc

Index: content/child/blink_platform_impl_unittest.cc
diff --git a/content/child/blink_platform_impl_unittest.cc b/content/child/blink_platform_impl_unittest.cc
index c1b6a8e405e2bb5a9e5e07dfcb2d6749cc1bdf2d..01a3b9180be09a8ef114dc88af6967feba5ba972 100644
--- a/content/child/blink_platform_impl_unittest.cc
+++ b/content/child/blink_platform_impl_unittest.cc
@@ -19,7 +19,7 @@ class TestBlinkPlatformImpl : public BlinkPlatformImpl {
   TestBlinkPlatformImpl() : mock_monotonically_increasing_time_(0) {}
 
   // Returns mock time when enabled.
-  virtual double monotonicallyIncreasingTime() override {
+  double monotonicallyIncreasingTime() override {
     if (mock_monotonically_increasing_time_ > 0.0)
       return mock_monotonically_increasing_time_;
     return BlinkPlatformImpl::monotonicallyIncreasingTime();