Clean up ui::TableModel.

- Reduce the size of the header.
- Break a big DCHECK() into several smaller DCHECK() calls.
- Use nullptr.

Change-Id: I94d060e0f63fc8e6e66e9bf429c534508a5f785f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3352610
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>
Cr-Commit-Position: refs/heads/main@{#956548}

ui/base/models/table_model.cc

@@ -7,6 +7,7 @@
 #include "base/check.h"
 #include "base/i18n/string_compare.h"
 #include "base/notreached.h"
+#include "third_party/icu/source/i18n/unicode/coll.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/models/image_model.h"
 
@@ -43,7 +44,7 @@ TableColumn& TableColumn::operator=(const TableColumn& other) = default;
 // TableModel -----------------------------------------------------------------
 
 // Used for sorting.
-static icu::Collator* g_collator = NULL;
+static icu::Collator* g_collator = nullptr;
 
 ui::ImageModel TableModel::GetIcon(int row) {
   return ui::ImageModel();
@@ -54,8 +55,11 @@ std::u16string TableModel::GetTooltip(int row) {
 }
 
 int TableModel::CompareValues(int row1, int row2, int column_id) {
-  DCHECK(row1 >= 0 && row1 < RowCount() &&
-         row2 >= 0 && row2 < RowCount());
+  DCHECK_GE(row1, 0);
+  DCHECK_LT(row1, RowCount());
+  DCHECK_GE(row2, 0);
+  DCHECK_LT(row2, RowCount());
+
   std::u16string value1 = GetText(row1, column_id);
   std::u16string value2 = GetText(row2, column_id);
   icu::Collator* collator = GetCollator();
@@ -69,15 +73,17 @@ int TableModel::CompareValues(int row1, int row2, int column_id) {
 
 void TableModel::ClearCollator() {
   delete g_collator;
-  g_collator = NULL;
+  g_collator = nullptr;
 }
 
+TableModel::~TableModel() = default;
+
 icu::Collator* TableModel::GetCollator() {
   if (!g_collator) {
     UErrorCode create_status = U_ZERO_ERROR;
     g_collator = icu::Collator::createInstance(create_status);
     if (!U_SUCCESS(create_status)) {
-      g_collator = NULL;
+      g_collator = nullptr;
       NOTREACHED();
     }
   }

ui/base/models/table_model.h

@@ -6,10 +6,14 @@
 #define UI_BASE_MODELS_TABLE_MODEL_H_
 
 #include <string>
-#include <vector>
 
 #include "base/component_export.h"
-#include "third_party/icu/source/i18n/unicode/coll.h"
+#include "third_party/icu/source/common/unicode/uversion.h"
+
+// third_party/icu/source/common/unicode/uversion.h will set namespace icu.
+namespace U_ICU_NAMESPACE {
+class Collator;
+}
 
 namespace ui {
 
@@ -55,7 +59,7 @@ class COMPONENT_EXPORT(UI_BASE) TableModel {
   void ClearCollator();
 
  protected:
-  virtual ~TableModel() {}
+  virtual ~TableModel();
 
   // Returns the collator used by CompareValues.
   icu::Collator* GetCollator();