Adding use_system_libusb option for third_party/libusb

third_party/libusb/libusb.gyp

Index: third_party/libusb/libusb.gyp
diff --git a/third_party/libusb/libusb.gyp b/third_party/libusb/libusb.gyp
index 6c5ffd4656d92349bd493d487c2dd36135c77967..4fc0c7e6b9061108b2bff63121ecc54948e48b70 100644
--- a/third_party/libusb/libusb.gyp
+++ b/third_party/libusb/libusb.gyp
@@ -3,63 +3,88 @@
 # found in the LICENSE file.
 
 {
+  'variables': {
+    'use_system_libusb%': 0,
+  },
   'targets': [
     {
       'target_name': 'libusb',
-      'type': '<(library)',
-      'sources': [
-        'libusb/core.c',
-        'libusb/descriptor.c',
-        'libusb/io.c',
-        'libusb/sync.c',
-      ],
-      'include_dirs': [
-        '.',
-        'libusb',
-        'libusb/os',
-      ],
       'conditions': [
-        [ 'OS == "linux"', {
-          'sources': [
-            'libusb/os/linux_usbfs.c',
-            'libusb/os/threads_posix.c',
-          ],
-          'defines': [
-            'DEFAULT_VISIBILITY=',
-            'HAVE_POLL_H=1',
-            'HAVE_SYS_TIME_H=1',
-            'OS_LINUX=1',
-            'POLL_NFDS_TYPE=nfds_t',
-            'THREADS_POSIX=1',
-            '_GNU_SOURCE=1',
-          ],
-        }],
-        [ 'OS == "win"', {
+        ['OS == "linux" and use_system_libusb', {
+          'type': 'none',
+          'direct_dependent_settings': {
+            'defines': [
+              'USE_SYSTEM_LIBUSB',
+            ],
+            'cflags': [
+              '<!@(pkg-config --cflags libusb-1.0)',
+            ],
+            'link_settings': {
+              'ldflags': [
+                '<!@(pkg-config --libs-only-L --libs-only-other libusb-1.0)',
+              ],
+              'libraries': [
+                '<!@(pkg-config --libs-only-l libusb-1.0)',
+              ],
+            },
+          },
+        }, {
+          'type': '<(library)',
           'sources': [
-            'libusb/os/poll_windows.c',
-            'libusb/os/threads_windows.c',
-            'libusb/os/windows_usb.c',
-          ],
-          'include_dirs!': [
-            '.',
+            'src/libusb/core.c',
+            'src/libusb/descriptor.c',
+            'src/libusb/io.c',
+            'src/libusb/sync.c',
           ],
           'include_dirs': [
-            'msvc',
-          ],
-        }],
-        [ 'OS == "mac"', {
-          'sources': [
-            'libusb/os/darwin_usb.c',
-            'libusb/os/threads_posix.c',
+            'src',
+            'src/libusb',
+            'src/libusb/os',
           ],
-          'defines': [
-            'DEFAULT_VISIBILITY=',
-            'HAVE_POLL_H=1',
-            'HAVE_SYS_TIME_H=1',
-            'OS_DARWIN=1',
-            'POLL_NFDS_TYPE=nfds_t',
-            'THREADS_POSIX=1',
-            '_GNU_SOURCE=1',
+          'conditions': [
+            [ 'OS == "linux"', {
+              'sources': [
+                'src/libusb/os/linux_usbfs.c',
+                'src/libusb/os/threads_posix.c',
+              ],
+              'defines': [
+                'DEFAULT_VISIBILITY=',
+                'HAVE_POLL_H=1',
+                'HAVE_SYS_TIME_H=1',
+                'OS_LINUX=1',
+                'POLL_NFDS_TYPE=nfds_t',
+                'THREADS_POSIX=1',
+                '_GNU_SOURCE=1',
+              ],
+            }],
+            ['OS == "win"', {
+              'sources': [
+                'src/libusb/os/poll_windows.c',
+                'src/libusb/os/threads_windows.c',
+                'src/libusb/os/windows_usb.c',
+              ],
+              'include_dirs!': [
+                'src',
+              ],
+              'include_dirs': [
+                'src/msvc',
+              ],
+            }],
+            ['OS == "mac"', {
+              'sources': [
+                'src/libusb/os/darwin_usb.c',
+                'src/libusb/os/threads_posix.c',
+              ],
+              'defines': [
+                'DEFAULT_VISIBILITY=',
+                'HAVE_POLL_H=1',
+                'HAVE_SYS_TIME_H=1',
+                'OS_DARWIN=1',
+                'POLL_NFDS_TYPE=nfds_t',
+                'THREADS_POSIX=1',
+                '_GNU_SOURCE=1',
+              ],
+            }],
           ],
         }],
       ],