Inline histograme name in SavePasswordsPreferences.java

The histogram name "PasswordManager.Android.PasswordSearchTriggered"
is put in a String constant in SavePasswordsPreferences. There are two
reasons to inline it instead:
(1) Inlining allows better presubmit checks for undefined histogram
    names.
(2) There is only one place where the String constant is used, anyway.

This CL inlines the histogram name.

Bug: 821823
Change-Id: I16d5ed0e23e3402d0307f537eb904ae7220a2c5b
Reviewed-on: https://chromium-review.googlesource.com/964842Reviewed-by: Theresa <twellington@chromium.org>
Commit-Queue: Vaclav Brozek <vabr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543672}

chrome/android/java/src/org/chromium/chrome/browser/preferences/password/SavePasswordsPreferences.java

@@ -125,11 +125,6 @@ public class SavePasswordsPreferences
     // Name of the subdirectory in cache which stores the exported passwords file.
     private static final String PASSWORDS_CACHE_DIR = "/passwords";
 
-    // Name of the histogram that records whether the user visiting the settings triggered the
-    // search.
-    private static final String HISTOGRAM_SEARCH_TRIGGERED =
-            "PasswordManager.Android.PasswordSearchTriggered";
-
     // Potential values of the histogram recording the result of exporting. This needs to match
     // ExportPasswordsResult from
     // //components/password_manager/core/browser/password_manager_metrics_util.h.
@@ -302,7 +297,8 @@ public class SavePasswordsPreferences
     private void maybeRecordTriggeredPasswordSearch(boolean searchTriggered) {
         if (providesPasswordSearch() && !mSearchRecorded) {
             mSearchRecorded = true;
-            RecordHistogram.recordBooleanHistogram(HISTOGRAM_SEARCH_TRIGGERED, searchTriggered);
+            RecordHistogram.recordBooleanHistogram(
+                    "PasswordManager.Android.PasswordSearchTriggered", searchTriggered);
         }
     }