Fix "unused variable" warnings.

ui/gl/sync_control_vsync_provider.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/gl/sync_control_vsync_provider.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "base/trace_event/trace_event.h"
 #include "build/build_config.h"
 
 #if defined(OS_LINUX)
 // These constants define a reasonable range for a calculated refresh interval.
 // Calculating refreshes out of this range will be considered a fatal error.
 const int64_t kMinVsyncIntervalUs = base::Time::kMicrosecondsPerSecond / 400;
 const int64_t kMaxVsyncIntervalUs = base::Time::kMicrosecondsPerSecond / 10;
 
 // How much noise we'll tolerate between successive computed intervals before
 // we think the latest computed interval is invalid (noisey due to
 // monitor configuration change, moving a window between monitors, etc.).
 const double kRelativeIntervalDifferenceThreshold = 0.05;
 #endif
 
 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() {}
 
 void SyncControlVSyncProvider::GetVSyncParameters(
     const UpdateVSyncCallback& callback) {
   TRACE_EVENT0("gpu", "SyncControlVSyncProvider::GetVSyncParameters");
 #if defined(OS_LINUX)
   base::TimeTicks timebase;
 
@@ skipping 107 matching lines @@
     }
   }
 
   last_timebase_ = timebase;
   last_media_stream_counter_ = media_stream_counter;
   callback.Run(timebase, last_good_interval_);
 #endif  // defined(OS_LINUX)
 }
 
 }  // namespace gfx