Compile FileCache related files only on Chrome OS.

chrome/browser/BUILD.gn

Index: chrome/browser/BUILD.gn
diff --git a/chrome/browser/BUILD.gn b/chrome/browser/BUILD.gn
index b374bc5980a3a9594c0bec4c5b231fd65cd03518..9b69383bea7bc2c6f0c3663f54ba98ab3a77f175 100644
--- a/chrome/browser/BUILD.gn
+++ b/chrome/browser/BUILD.gn
@@ -455,6 +455,9 @@ source_set("browser") {
     sources += rebase_path(gypi_values.chrome_browser_extensions_sources,
                            ".",
                            "//chrome")
+    if (is_chromeos) {
+      deps += [ "//components/drive:drive_chromeos" ]

[hashimoto, 2016/01/22 05:39:22]

Isn't it better to put this in chrome/browser/chromeos/BUILD.gn?

[yawano, 2016/01/22 06:18:59]

Done.

+    }
   }
   if (enable_background) {
     sources += rebase_path(gypi_values.chrome_browser_background_sources,
@@ -1283,6 +1286,10 @@ source_set("test_support") {
       "//components/drive:test_support",
       "//components/storage_monitor:test_support",
     ]
+
+    if (is_chromeos) {
+      deps += [ "//components/drive:test_support_chromeos" ]
+    }
   }
 
   if (enable_mdns) {