Make a copy of PageClassification enum outside the metrics code

chrome/browser/autocomplete/autocomplete_input.h

Index: chrome/browser/autocomplete/autocomplete_input.h
diff --git a/chrome/browser/autocomplete/autocomplete_input.h b/chrome/browser/autocomplete/autocomplete_input.h
index d70a3afa1e10c034a4811c0141b64652e25529df..ae9ea45e876cc1da8fef49311e28f0908643e23f 100644
--- a/chrome/browser/autocomplete/autocomplete_input.h
+++ b/chrome/browser/autocomplete/autocomplete_input.h
@@ -44,6 +44,29 @@ class AutocompleteInput {
     ALL_MATCHES,
   };
 
+  // The type of page currently displayed.
+  // Note: when adding an element to this enum, please add it at the end
+  // and update omnibox_event.proto::PageClassification and
+  // omnibox_edit_model.cc::ClassifyPage() too.
+  enum PageClassification {
+    INVALID_SPEC = 0,   // invalid URI; shouldn't happen

[Peter Kasting, 2013/07/26 18:06:38]

Nit: I think you mean URL.  (Generally we don't work with URIs that aren't
URLs...)

Also, I suggest putting all the comments for each value above the value, rather
than some beside and some below.  Then I'd probably put a blank line between
each (comment + code) block and the next.

[Mark P, 2013/07/26 18:45:39]

I'd rather do this cleanup in a separate changelist so it's more obvious to see
what we change.

Furthermore, because I have to do these suggestions in three places (here,
OmniboxEventProto in chromium source tree, OmniboxEventProto in google source
tree), it makes sense to try to separate that out from this refactoring.

+    NEW_TAB_PAGE = 1,   // chrome://newtab/
+    // Note that chrome://newtab/ doesn't have to be the built-in
+    // version; it could be replaced by an extension.
+    BLANK = 2,          // about:blank
+    HOMEPAGE = 3,       // user switched settings to "open this page" mode.
+    // Note that if the homepage is set to the new tab page or about blank,
+    // then we'll classify the web page into those categories, not HOMEPAGE.
+    OTHER = 4,          // everything not included somewhere else on this list
+    INSTANT_NEW_TAB_PAGE = 5,  // new tab page rendered by Instant

[Peter Kasting, 2013/07/26 18:06:38]

Nit: Might want to note the instant exception on NEW_TAB_PAGE above.

[Mark P, 2013/07/26 18:45:39]

ditto.

+    // The user is on a search result page that's doing search term
+    // replacement, meaning the search terms should've appeared in the omnibox
+    // before the user started editing it, not the URL of the page.
+    SEARCH_RESULT_PAGE_DOING_SEARCH_TERM_REPLACEMENT = 6
+    // Please duplicate all changes to this enum in omnibox_event.proto;
+    // see note at the top of this enum.

[Peter Kasting, 2013/07/26 18:06:38]

Nit: Don't duplicate this comment from above.

[Mark P, 2013/07/26 18:45:39]

Removed.

+  };
+
   AutocompleteInput();
   // |text| and |cursor_position| represent the input query and location of
   // the cursor with the query respectively.  |cursor_position| may be set to