Add a new metric for how many times permissions prompts are shown.

chrome/browser/ui/website_settings/permission_bubble_request.h

Index: chrome/browser/ui/website_settings/permission_bubble_request.h
diff --git a/chrome/browser/ui/website_settings/permission_bubble_request.h b/chrome/browser/ui/website_settings/permission_bubble_request.h
index 9da18802c0140d08db1ec94f16a90e49603ec84c..57b08d4ed28cde6cfcc828aeddec2be0c30b50bd 100644
--- a/chrome/browser/ui/website_settings/permission_bubble_request.h
+++ b/chrome/browser/ui/website_settings/permission_bubble_request.h
@@ -12,6 +12,24 @@ namespace gfx {
 enum class VectorIconId;
 }
 
+// Used for UMA to record the types of permission prompts shown.
+// This corresponds to the PermissionPromptType enum in
+// src/tools/metrics/histograms.xml. The usual rules of updating UMA values
+// applies to this enum:
+// - don't remove values
+// - only ever add values at the end
+// - keep the PermissionPromptType enum in sync with this definition.

[felt, 2016/04/18 21:15:14]

"Your search - PermissionPromptType - did not match any documents." 
which enum do you mean?

also, in general, I am very wary of requiring future people who update enums to
keep two enums in sync.

[benwells, 2016/04/19 00:09:24]

I don't know of any way to get around needing the two enums. The one in
histograms.xml is just a description of this one for reporting in the UMA front
end.

However I think I should name the enums the same to make it clearer. I had kept
the UMA one more general in case it one day needs to refer to more than just
bubbles (e.g. infobars), but if that ever happens we can just rename it then.

[felt, 2016/04/19 00:21:19]

Ohhhh, I missed that this was the name of the enum in histograms.xml. I thought
you were referring to a histogram somewhere else in C++ code that I couldn't
find. I am not concerned anymore now that I see what was meant.

+enum class PermissionBubbleType {
+  UNKNOWN,
+  MULTIPLE,
+  PERMISSION,
+  QUOTA,
+  DOWNLOAD,
+  MEDIA_STREAM,
+  REGISTER_PROTOCOL_HANDLER,
+  NUM
+};
+
 // Describes the interface a feature utilizing permission bubbles should
 // implement. A class of this type is registered with the permission bubble
 // manager to receive updates about the result of the permissions request
@@ -62,6 +80,8 @@ class PermissionBubbleRequest {
   // no further message from the permission bubble system. This method will
   // eventually be called on every request which is not unregistered.
   virtual void RequestFinished() = 0;
+
+  virtual PermissionBubbleType GetPermissionBubbleType() const;
 };
 
 #endif  // CHROME_BROWSER_UI_WEBSITE_SETTINGS_PERMISSION_BUBBLE_REQUEST_H_