Add support for the 'webview_android' policy configuration

grit/format/policy_templates/writers/template_writer.py

Index: grit/format/policy_templates/writers/template_writer.py
diff --git a/grit/format/policy_templates/writers/template_writer.py b/grit/format/policy_templates/writers/template_writer.py
index d489d648c3767e9a1d94e57e851745abf52b4d76..4a23ff5a606553e08c46468f384b8df28da17fe4 100644
--- a/grit/format/policy_templates/writers/template_writer.py
+++ b/grit/format/policy_templates/writers/template_writer.py
@@ -91,7 +91,7 @@ class TemplateWriter(object):
     '''Checks if the given policy can be mandatory.'''
     return policy.get('features', {}).get('can_be_mandatory', True)
 
-  def IsPolicySupportedOnPlatform(self, policy, platform):
+  def IsPolicySupportedOnPlatform(self, policy, platform, product=None):
     '''Checks if |policy| is supported on |platform|.
 
     Args:
@@ -99,7 +99,14 @@ class TemplateWriter(object):
       platform: The platform to check; one of 'win', 'mac', 'linux' or
         'chrome_os'.
     '''
-    is_supported = lambda x: platform in x['platforms']
+
+    def is_supported(supported_on):
+      if not platform in supported_on['platforms']:
+        return None
+      if product and not product in supported_on['product']:
+        return None
+      return supported_on
+
     return any(filter(is_supported, policy['supported_on']))
 
   def _GetChromiumVersionString(self):