longpress diacritics: Add metric for char code for diacritics.

Using sparse histogram so arbitrary integer values are okay even if not
enumerated in the enum.xml. I enumerated all 68 diacritical character
char codes in the xml for easy metric analysis.

Bug: b/241729161
Change-Id: I8ff81d1fd37e749aab418449d789354ebabc0559
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3825680
Reviewed-by: Darren Shen <shend@chromium.org>
Reviewed-by: Keith Lee <keithlee@chromium.org>
Auto-Submit: jhtin <jhtin@chromium.org>
Commit-Queue: jhtin <jhtin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1034972}

chrome/browser/ash/input_method/longpress_diacritics_suggester.cc

@@ -9,6 +9,7 @@
 
 #include "base/containers/flat_map.h"
 #include "base/logging.h"
+#include "base/metrics/histogram_functions.h"
 #include "base/no_destructor.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ -43,6 +44,21 @@ AssistiveWindowButton CreateButtonFor(size_t index,
   return button;
 }
 
+void RecordAcceptanceCharCodeMetric(const std::u16string diacritic) {
+  // Recording -1 as default value just in case there are issues with
+  // encoding in utf-16 that means some character isn't
+  // properly captured in one utf-16 char (for example if emojis are added in
+  // the future).
+  int char_code = -1;
+  if (diacritic.length() == 1) {
+    char_code = int(diacritic[0]);
+  }
+
+  base::UmaHistogramSparse(
+      "InputMethod.PhysicalKeyboard.LongpressDiacritics.AcceptedChar",
+      char_code);
+}
+
 }  // namespace
 
 LongpressDiacriticsSuggester::LongpressDiacriticsSuggester(
@@ -200,7 +216,7 @@ bool LongpressDiacriticsSuggester::AcceptSuggestion(size_t index) {
     LOG(ERROR) << "Failed to accept suggestion. " << error;
     return false;
   }
-
+  RecordAcceptanceCharCodeMetric(current_suggestions[index]);
   Reset();
   return true;
 }

chrome/browser/ash/input_method/longpress_diacritics_suggester_unittest.cc

@@ -8,6 +8,7 @@
 
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
+#include "base/test/metrics/histogram_tester.h"
 #include "chrome/browser/ash/input_method/fake_suggestion_handler.h"
 #include "chrome/browser/ash/input_method/suggestion_enums.h"
 #include "chrome/test/base/testing_profile.h"
@@ -35,6 +36,19 @@ using AssistiveWindowButton = ui::ime::AssistiveWindowButton;
 
 const int kContextId = 24601;
 
+const auto kDigitToDomCode = base::MakeFixedFlatMap<int, ui::DomCode>({
+    {0, ui::DomCode::DIGIT0},
+    {1, ui::DomCode::DIGIT1},
+    {2, ui::DomCode::DIGIT2},
+    {3, ui::DomCode::DIGIT3},
+    {4, ui::DomCode::DIGIT4},
+    {5, ui::DomCode::DIGIT5},
+    {6, ui::DomCode::DIGIT6},
+    {7, ui::DomCode::DIGIT7},
+    {8, ui::DomCode::DIGIT8},
+    {9, ui::DomCode::DIGIT9},
+});
+
 ui::KeyEvent CreateKeyEventFromCode(const ui::DomCode& code) {
   return ui::KeyEvent(ui::ET_KEY_PRESSED, ui::VKEY_UNKNOWN, code, ui::EF_NONE,
                       ui::DomKey::NONE, ui::EventTimeForNow());
@@ -623,6 +637,32 @@ TEST_P(LongpressDiacriticsSuggesterTest, ReturnsDiacriticsProposeActionType) {
             AssistiveType::kLongpressDiacritics);
 }
 
+TEST_P(LongpressDiacriticsSuggesterTest, RecordsAcceptanceCharCodeMetric) {
+  base::HistogramTester histogram_tester;
+
+  FakeSuggestionHandler suggestion_handler;
+  LongpressDiacriticsSuggester suggester =
+      LongpressDiacriticsSuggester(&suggestion_handler);
+  suggester.OnFocus(kContextId);
+
+  int histogram_accept_count = 0;
+  for (int i = 0; i < 9 && i < GetParam().candidates.size(); i++) {
+    // Insert using dom code for index + 1 (i.e. DIGIT1 inserts 0th index
+    // candidate)
+    ui::DomCode dom_code = kDigitToDomCode.find(i + 1)->second;
+    suggester.TrySuggestOnLongpress(GetParam().longpress_char);
+    suggester.HandleKeyEvent(CreateKeyEventFromCode(dom_code));
+
+    histogram_tester.ExpectTotalCount(
+        "InputMethod.PhysicalKeyboard.LongpressDiacritics.AcceptedChar",
+        ++histogram_accept_count);
+    int char_code = int(GetParam().candidates[i][0]);
+    histogram_tester.ExpectBucketCount(
+        "InputMethod.PhysicalKeyboard.LongpressDiacritics.AcceptedChar",
+        char_code, 1);
+  }
+}
+
 INSTANTIATE_TEST_SUITE_P(
     /* no prefix */,
     LongpressDiacriticsSuggesterTest,

tools/metrics/histograms/enums.xml

@@ -50054,6 +50054,83 @@ Called by update_gpu_driver_bug_workaround_entries.py.-->
   <int value="2" label="UNDO"/>
 </enum>
 
+<enum name="IMEPKLongpressDiacriticUnicodeCharacterCode">
+<!--
+Do not add the actual diacritical or non basic ascii characters to the text of this file.
+Unsupported non-ascii characters will cause issues with xml presubmits.
+  -->
+
+  <int value="-1" label="UNKOWN CHARACTER"/>
+  <int value="192" label="Latin Capital Letter A with grave"/>
+  <int value="193" label="Latin Capital letter A with acute"/>
+  <int value="194" label="Latin Capital letter A with circumflex"/>
+  <int value="195" label="Latin Capital letter A with tilde"/>
+  <int value="196" label="Latin Capital letter A with diaeresis"/>
+  <int value="197" label="Latin Capital letter A with ring above"/>
+  <int value="198" label="Latin Capital letter AE"/>
+  <int value="199" label="Latin Capital letter C with cedilla"/>
+  <int value="200" label="Latin Capital letter E with grave"/>
+  <int value="201" label="Latin Capital letter E with acute"/>
+  <int value="202" label="Latin Capital letter E with circumflex"/>
+  <int value="203" label="Latin Capital letter E with diaeresis"/>
+  <int value="204" label="Latin Capital letter I with grave"/>
+  <int value="205" label="Latin Capital letter I with acute"/>
+  <int value="206" label="Latin Capital letter I with circumflex"/>
+  <int value="207" label="Latin Capital letter I with diaeresis"/>
+  <int value="209" label="Latin Capital letter N with tilde"/>
+  <int value="210" label="Latin Capital letter O with grave"/>
+  <int value="211" label="Latin Capital letter O with acute"/>
+  <int value="212" label="Latin Capital letter O with circumflex"/>
+  <int value="213" label="Latin Capital letter O with tilde"/>
+  <int value="214" label="Latin Capital letter O with diaeresis"/>
+  <int value="216" label="Latin Capital letter O with stroke"/>
+  <int value="217" label="Latin Capital letter U with grave"/>
+  <int value="218" label="Latin Capital letter U with acute"/>
+  <int value="219" label="Latin Capital Letter U with circumflex"/>
+  <int value="220" label="Latin Capital Letter U with diaeresis"/>
+  <int value="223" label="Latin Small Letter sharp S"/>
+  <int value="224" label="Latin Small Letter A with grave"/>
+  <int value="225" label="Latin Small Letter A with acute"/>
+  <int value="226" label="Latin Small Letter A with circumflex"/>
+  <int value="227" label="Latin Small Letter A with tilde"/>
+  <int value="228" label="Latin Small Letter A with diaeresis"/>
+  <int value="229" label="Latin Small Letter A with ring above"/>
+  <int value="230" label="Latin Small Letter AE"/>
+  <int value="231" label="Latin Small Letter C with cedilla"/>
+  <int value="232" label="Latin Small Letter E with grave"/>
+  <int value="233" label="Latin Small Letter E with acute"/>
+  <int value="234" label="Latin Small Letter E with circumflex"/>
+  <int value="235" label="Latin Small Letter E with diaeresis"/>
+  <int value="236" label="Latin Small Letter I with grave"/>
+  <int value="237" label="Latin Small Letter I with acute"/>
+  <int value="238" label="Latin Small Letter I with circumflex"/>
+  <int value="239" label="Latin Small Letter I with diaeresis"/>
+  <int value="241" label="Latin Small Letter N with tilde"/>
+  <int value="242" label="Latin Small Letter O with grave"/>
+  <int value="243" label="Latin Small Letter O with acute"/>
+  <int value="244" label="Latin Small Letter O with circumflex"/>
+  <int value="245" label="Latin Small Letter O with tilde"/>
+  <int value="246" label="Latin Small Letter O with diaeresis"/>
+  <int value="248" label="Latin Small Letter O with stroke"/>
+  <int value="249" label="Latin Small Letter U with grave"/>
+  <int value="250" label="Latin Small Letter U with acute"/>
+  <int value="251" label="Latin Small Letter U with circumflex"/>
+  <int value="252" label="Latin Small Letter U with diaeresis"/>
+  <int value="256" label="Latin Capital Letter A with macron"/>
+  <int value="257" label="Latin Small Letter A with macron"/>
+  <int value="274" label="Latin Capital Letter E with macron"/>
+  <int value="275" label="Latin Small Letter E with macron"/>
+  <int value="298" label="Latin Capital Letter I with macron"/>
+  <int value="299" label="Latin Small Letter I with macron"/>
+  <int value="332" label="Latin Capital Letter O with macron"/>
+  <int value="333" label="Latin Small Letter O with macron"/>
+  <int value="338" label="Latin Capital Ligature OE"/>
+  <int value="339" label="Latin Small Ligature OE"/>
+  <int value="362" label="Latin Capital Letter U with macron"/>
+  <int value="363" label="Latin Small Letter U with macron"/>
+  <int value="7838" label="Capital sharp s, German"/>
+</enum>
+
 <enum name="IMERegisterProxyView">
   <obsolete>
     Removed as of Jan 2020.

tools/metrics/histograms/metadata/input/histograms.xml

@@ -773,6 +773,17 @@ chromium-metrics-reviews@google.com.
   </summary>
 </histogram>
 
+<histogram name="InputMethod.PhysicalKeyboard.LongpressDiacritics.AcceptedChar"
+    enum="IMEPKLongpressDiacriticUnicodeCharacterCode"
+    expires_after="2023-08-08">
+  <owner>jhtin@chromium.org</owner>
+  <owner>essential-inputs-team@google.com</owner>
+  <summary>
+    The unicode code point for the diacritic or character variant accepted by a
+    user using longpress diacritics on physical keyboard.
+  </summary>
+</histogram>
+
 <histogram name="InputMethod.PkCommit.Index" units="units"
     expires_after="2021-10-10">
   <owner>shend@chromium.org</owner>