Fix "unused variable" warnings.

ui/gl/sync_control_vsync_provider.cc

Index: ui/gl/sync_control_vsync_provider.cc
diff --git a/ui/gl/sync_control_vsync_provider.cc b/ui/gl/sync_control_vsync_provider.cc
index c3ecb9563e77df5a40c64f790c33d09fa8f564b7..b363affa9f62e17527a42b402aced7e1bbc05a96 100644
--- a/ui/gl/sync_control_vsync_provider.cc
+++ b/ui/gl/sync_control_vsync_provider.cc
@@ -25,12 +25,13 @@ const double kRelativeIntervalDifferenceThreshold = 0.05;
 
 namespace gfx {
 
-SyncControlVSyncProvider::SyncControlVSyncProvider()
-    : VSyncProvider(), last_media_stream_counter_(0), invalid_msc_(false) {
+SyncControlVSyncProvider::SyncControlVSyncProvider() : VSyncProvider() {
+#if defined(OS_LINUX)

[sadrul, 2016/05/19 13:10:06]

It looks like this whole file is for linux only. Perhaps should be excluded on
non-linux platforms.

[Peter Kasting, 2016/05/19 18:03:45]

Yeah, I saw that -- it looks like we want to define these symbols for all
platforms but they're basically no-ops everywhere but Linux.  I think you're
right that it would make sense to put the Linux definitions in a Linux-specific
file.  I'd rather do that outside this change, though.

   // On platforms where we can't get an accurate reading on the refresh
   // rate we fall back to the assumption that we're displaying 60 frames
   // per second.
   last_good_interval_ = base::TimeDelta::FromSeconds(1) / 60;
+#endif
 }
 
 SyncControlVSyncProvider::~SyncControlVSyncProvider() {}