Add metric Omnibox.FocusToOpenTime for time from omnibox focus to omnibox usage.

chrome/browser/ui/omnibox/omnibox_edit_model.cc

Index: chrome/browser/ui/omnibox/omnibox_edit_model.cc
===================================================================
--- chrome/browser/ui/omnibox/omnibox_edit_model.cc	(revision 214454)
+++ chrome/browser/ui/omnibox/omnibox_edit_model.cc	(working copy)
@@ -97,6 +97,10 @@
 // between focusing and editing the omnibox.
 const char kFocusToEditTimeHistogram[] = "Omnibox.FocusToEditTime";
 
+// Histogram name which counts the number of milliseconds a user takes
+// between focusing and opening an omnibox match.
+const char kFocusToOpenTimeHistogram[] = "Omnibox.FocusToOpenTime";
+
 void RecordPercentageMatchHistogram(const string16& old_text,
                                     const string16& new_text,
                                     bool search_term_replacement_active,
@@ -164,6 +168,7 @@
       controller_(controller),
       focus_state_(OMNIBOX_FOCUS_NONE),
       user_input_in_progress_(false),
+      user_input_since_focus_(true),
       just_deleted_text_(false),
       has_temporary_text_(false),
       paste_state_(NONE),
@@ -414,14 +419,11 @@
 }
 
 void OmniboxEditModel::SetInputInProgress(bool in_progress) {
-  if (in_progress && !last_omnibox_focus_without_user_input_.is_null()) {
+  if (in_progress && !user_input_since_focus_) {
     base::TimeTicks now = base::TimeTicks::Now();
-    DCHECK(last_omnibox_focus_without_user_input_ <= now);
-    UMA_HISTOGRAM_TIMES(kFocusToEditTimeHistogram,
-                        now - last_omnibox_focus_without_user_input_);
-    // We only want to count the time from focus to the first user input, so
-    // reset |last_omnibox_focus_without_user_input_| to null.
-    last_omnibox_focus_without_user_input_ = base::TimeTicks();
+    DCHECK(last_omnibox_focus_ <= now);
+    UMA_HISTOGRAM_TIMES(kFocusToEditTimeHistogram, now - last_omnibox_focus_);
+    user_input_since_focus_ = true;
   }
 
   if (user_input_in_progress_ == in_progress)
@@ -658,6 +660,7 @@
         content::Source<Profile>(profile_),
         content::Details<OmniboxLog>(&log));
     HISTOGRAM_ENUMERATION("Omnibox.EventCount", 1, 2);
+    UMA_HISTOGRAM_TIMES(kFocusToOpenTimeHistogram, now - last_omnibox_focus_);

[Mark P, 2013/08/02 19:29:51]

What happens if last_omnibox_focus_ is somehow null here? (i.e.,
user_input_since_focus is false)  I know it shouldn't happen but you should
think a bout what do you want to do in case it somehow does.

[Peter Kasting, 2013/08/02 19:31:06]

Sticking a DCHECK in front would be OK.  (I was actually OK with the code
without this.)

[H Fung, 2013/08/02 20:18:42]

Done.

   }
 
   TemplateURL* template_url = match.GetTemplateURL(profile_, false);
@@ -794,7 +797,8 @@
 }
 
 void OmniboxEditModel::OnSetFocus(bool control_down) {
-  last_omnibox_focus_without_user_input_ = base::TimeTicks::Now();
+  last_omnibox_focus_ = base::TimeTicks::Now();
+  user_input_since_focus_ = false;
 
   // If the omnibox lost focus while the caret was hidden and then regained
   // focus, OnSetFocus() is called and should restore visibility. Note that