Move device_sensors cross-process headers out of //content

device/sensors/public/cpp/BUILD.gn

Index: device/sensors/public/cpp/BUILD.gn
diff --git a/device/sensors/public/cpp/BUILD.gn b/device/sensors/public/cpp/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..e7b4601387823965d1d092f0eca3bd9e3930e158
--- /dev/null
+++ b/device/sensors/public/cpp/BUILD.gn
@@ -0,0 +1,17 @@
+# Copyright 2016 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.
+
+source_set("cpp") {
+  sources = [
+    "device_light_data.h",
+    "device_light_hardware_buffer.h",
+    "device_motion_hardware_buffer.h",
+    "device_orientation_hardware_buffer.h",
+  ]
+
+  public_deps = [
+    "//device/base/synchronization",
+    "//third_party/WebKit/public:blink_headers",
+  ]
+}