Remove android_webview_build conditions from base.

base/base.gypi

Index: base/base.gypi
diff --git a/base/base.gypi b/base/base.gypi
index 825bca1faf4ab38caeaed17cf9f5888e4c47122a..c3b6e9db6113cef78464ee0a1a18a7f9a89be98d 100644
--- a/base/base.gypi
+++ b/base/base.gypi
@@ -836,13 +836,6 @@
               ['include', '^threading/platform_thread_linux\\.cc$'],
             ],
           }],
-          ['OS == "android" and <(android_webview_build)==1', {
-            'defines': [
-               # WebView builds as part of the system which already has sincos;
-               # avoid defining it again as it causes a linker warning.
-               'ANDROID_SINCOS_PROVIDED',
-            ],
-          }],
           ['<(chromeos) == 1', {
             'sources!': [
               'power_monitor/power_monitor_device_source_posix.cc',