Fix "unused variable" warnings.

content/browser/device_sensors/data_fetcher_shared_memory.h

Index: content/browser/device_sensors/data_fetcher_shared_memory.h
diff --git a/content/browser/device_sensors/data_fetcher_shared_memory.h b/content/browser/device_sensors/data_fetcher_shared_memory.h
index 607cbb732726a4a4a54b4b2d403aadb9198dc100..976f309167ddd3138ef50d8ac099fad1e663c8cd 100644
--- a/content/browser/device_sensors/data_fetcher_shared_memory.h
+++ b/content/browser/device_sensors/data_fetcher_shared_memory.h
@@ -45,11 +45,14 @@ class CONTENT_EXPORT DataFetcherSharedMemory
   bool Start(ConsumerType consumer_type, void* buffer) override;
   bool Stop(ConsumerType consumer_type) override;
 
-#if !defined(OS_ANDROID)
-  DeviceMotionHardwareBuffer* motion_buffer_;
-  DeviceOrientationHardwareBuffer* orientation_buffer_;
-  DeviceOrientationHardwareBuffer* orientation_absolute_buffer_;
-  DeviceLightHardwareBuffer* light_buffer_;
+#if (defined(OS_LINUX) && !defined(OS_CHROMEOS)) || defined(OS_MACOSX) || \
+    defined(OS_WIN)
+  DeviceMotionHardwareBuffer* motion_buffer_ = nullptr;
+  DeviceOrientationHardwareBuffer* orientation_buffer_ = nullptr;
+  DeviceLightHardwareBuffer* light_buffer_ = nullptr;
+#endif
+#if defined(OS_LINUX) || defined(OS_MACOSX)
+  DeviceOrientationHardwareBuffer* orientation_absolute_buffer_ = nullptr;

[timvolodine, 2016/05/19 14:01:44]

yeah sorry, we actually need it for windows as well (i've just landed a patch),
so maybe just keep the "!defined(OS_ANDROID)" above..

[Peter Kasting, 2016/05/20 02:57:36]

I think that still has problems on platforms outside of (linux, mac, win), but
fixed in another way.

 #endif
 
 #if defined(OS_CHROMEOS)