Add metrics to help measure effects of installing default apps in a profile.

chrome/browser/ui/webui/ntp/new_tab_page_handler.h

Index: chrome/browser/ui/webui/ntp/new_tab_page_handler.h
===================================================================
--- chrome/browser/ui/webui/ntp/new_tab_page_handler.h	(revision 105055)
+++ chrome/browser/ui/webui/ntp/new_tab_page_handler.h	(working copy)
@@ -19,6 +19,7 @@
   virtual ~NewTabPageHandler() {}
 
   // WebUIMessageHandler implementation.
+  virtual WebUIMessageHandler* Attach(WebUI* web_ui) OVERRIDE;
   virtual void RegisterMessages() OVERRIDE;
 
   // Callback for "closeNotificationPromo".
@@ -53,10 +54,11 @@
   // group, and the rest of the bits are used for the page group ID (defined
   // here).
   enum {
-    INDEX_MASK = (1 << 10) - 1,
-    MOST_VISITED_PAGE_ID = 1 << 10,
-    APPS_PAGE_ID = 2 << 10,
-    BOOKMARKS_PAGE_ID = 3 << 10,
+    PAGE_ID_OFFSET = 10,

[Evan Stade, 2011/10/13 00:07:51]

do not add this as an enum value, it doesn't make sense

[Roger Tawa OOO till Jul 10th, 2011/10/13 00:39:43]

Done.

+    INDEX_MASK = (1 << PAGE_ID_OFFSET) - 1,
+    MOST_VISITED_PAGE_ID = 1 << PAGE_ID_OFFSET,
+    APPS_PAGE_ID = 2 << PAGE_ID_OFFSET,
+    BOOKMARKS_PAGE_ID = 3 << PAGE_ID_OFFSET,

[Evan Stade, 2011/10/13 00:07:51]

LAST_PAGE_ID = BOOKMARKS_PAGE_ID

[Roger Tawa OOO till Jul 10th, 2011/10/13 00:39:43]

Done.

[jar (doing other things), 2011/10/13 22:16:53]

This looks like you're going for a histogram with about 4K buckets, which is
probably much larger than you need.  The cost is about 4 bytes per bucket
contents, plus 4 bytes to define the range stored in teh bucket, or a total of 8
bytes per bucket, and around 32K total.   ...but... UMA also needs a snapshot to
send up deltas, so that may mean it may cost closer to 64K total :-(.

I suspect you're gather much more data than you need, as I don't know how all
this data will be used (or analyzed).  64K isn't the end of the world... but it
is a measurable fraction of memory utilization.

[jar (doing other things), 2011/10/13 22:22:07]

I retract my comment.  Sorry about that.... the histogram scales back down the
size.

On 2011/10/13 22:16:53, jar wrote:

   };
 
   // Helper to send out promo resource change notification.