Use cpu_features library from ndk when built with chromium.

In Chromium on Andorid, nkd provides cpu_features library so that all modules using that library can link against it to avoid function re-definition.
Review URL: https://webrtc-codereview.appspot.com/937024

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3127 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/system_wrappers/source/cpu_features_android.c

@@ -8,7 +8,11 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
+#if defined(WEBRTC_CHROMIUM_BUILD)
+#include <cpu-features.h>
+#else
 #include "android/cpu-features.h"
+#endif  //  defined(WEBRTC_CHROMIUM_BUILD)
 
 uint64_t WebRtc_GetCPUFeaturesARM(void) {
   return android_getCpuFeatures();

webrtc/system_wrappers/source/system_wrappers.gyp

@@ -192,12 +192,22 @@
           'target_name': 'cpu_features_android',
           'type': '<(library)',
           'sources': [
-            'android/cpu-features.c',
-            'android/cpu-features.h',
             # TODO(leozwang): Ideally we want to audomatically exclude .c files
             # as with .cc files, gyp currently only excludes .cc files.
             'cpu_features_android.c',
           ],
+          'conditions': [
+            ['build_with_chromium==1', {
+              'dependencies': [
+                '<(android_ndk_root)/android_tools_ndk.gyp:cpu_features',
+              ],
+            }, {
+              'sources': [
+                'android/cpu-features.c',
+                'android/cpu-features.h',
+              ],
+            }],
+          ],
         },
       ],
     }],