Add UMA for the new generic permisison class

chrome/browser/content_settings/permission_context_base.h

Index: chrome/browser/content_settings/permission_context_base.h
diff --git a/chrome/browser/content_settings/permission_context_base.h b/chrome/browser/content_settings/permission_context_base.h
index 76bbc91137b615688b3c4b4b1e2e4d802138c25d..7452698252126da2c45622991ba15601b6e6770b 100644
--- a/chrome/browser/content_settings/permission_context_base.h
+++ b/chrome/browser/content_settings/permission_context_base.h
@@ -22,6 +22,17 @@ namespace content {
 class WebContents;
 }
 
+// Enum for UMA purposes, make sure you update histograms.xml if you
+// add new pemissions.

[Mark P, 2014/07/08 20:49:03]

Please explicitly use = 0, = 1, and so on.  Also say to never delete or reorder
an entry; only add new entries immediately before PERMISSION_NUM.

+enum PermissionType {
+  PERMISSION_UNKNOWN,
+  PERMISSION_MIDI_SYSEX,
+  PERMISSION_PUSH_MESSAGING,
+
+  // Always keep this at the end.
+  PERMISSION_NUM,

[Mark P, 2014/07/08 20:49:03]

optional nit: consider PERMISSION_MAX

[Miguel Garcia, 2014/07/09 11:17:19]

Done.

+};
+
 typedef base::Callback<void(bool)> BrowserPermissionCallback;
 
 // This base class contains common operations for granting permissions.
@@ -79,6 +90,7 @@ class PermissionContextBase : public KeyedService {
                          const GURL& requesting_origin,
                          const GURL& embedder_origin,
                          const BrowserPermissionCallback& callback,
+                         bool persist,
                          bool allowed);
 
   void NotifyPermissionSet(const PermissionRequestID& id,