prepare skia for shared library build on android

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
 #    'SK_SUPPORT_HINTING_SCALE_FACTOR',
   ],
   'conditions' : [
     [ 'skia_gpu == 1',
       {
@@ skipping 308 matching lines @@
         ],
         'conditions': [
           [ 'skia_warnings_as_errors', {
             'cflags': [
               '-Werror',
             ],
           }],
           [ 'skia_profile_enabled == 1', {
             'cflags': ['-g', '-fno-omit-frame-pointer', '-marm', '-mapcs'],
           }],
+          [ 'skia_shared_lib', {
+            'cflags': [
+              '-fPIC',
+            ],
+            'defines': [
+              'GR_DLL=1',
+              'GR_IMPLEMENTATION=1',
+              'SKIA_DLL',
+              'SKIA_IMPLEMENTATION=1',
+            ],
+          }],
           [ 'skia_arch_type == "arm" and arm_thumb == 1', {
             'cflags': [
               '-mthumb',
             ],
           }],
           [ 'skia_arch_type == "arm" and armv7 == 1', {
             'variables': {
               'arm_neon_optional%': 0,
             },
             'defines': [
@@ skipping 39 matching lines @@
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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