Introduce unittest for passing NULL pointer for actual_range.

content/browser/renderer_host/render_widget_host_view_mac_unittest.mm

Index: content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
diff --git a/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm b/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
index 6f140ba0f6557b726e1bab7709b0faaaeff9a816..5ad0070675a68487f3fff385c1eafe04aa6dc7d0 100644
--- a/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
+++ b/content/browser/renderer_host/render_widget_host_view_mac_unittest.mm
@@ -337,8 +337,14 @@ TEST_F(RenderWidgetHostViewMacTest, UpdateCompositionSinglelineCase) {
   const gfx::Point kOrigin(10, 11);
   const gfx::Size kBoundsUnit(10, 20);
 
-  // If there are no update from renderer, always returned caret position.
   NSRect rect;
+  // Make sure not crashing by passing NULL pointer instead of |actual_range|.
+  EXPECT_FALSE(rwhv_mac_->GetCachedFirstRectForCharacterRange(
+      ui::Range(0, 0).ToNSRange(),
+      &rect,
+      NULL));
+
+  // If there are no update from renderer, always returned caret position.
   NSRange actual_range;
   EXPECT_FALSE(rwhv_mac_->GetCachedFirstRectForCharacterRange(
       ui::Range(0, 0).ToNSRange(),
@@ -415,6 +421,13 @@ TEST_F(RenderWidgetHostViewMacTest, UpdateCompositionSinglelineCase) {
             &actual_range));
       EXPECT_EQ(ui::Range(request_range), ui::Range(actual_range));
       EXPECT_EQ(expected_rect, gfx::Rect(NSRectToCGRect(rect)));
+
+      // Make sure not crashing by passing NULL pointer instead of
+      // |actual_range|.
+      EXPECT_TRUE(rwhv_mac_->GetCachedFirstRectForCharacterRange(
+            request_range,
+            &rect,
+            NULL));
     }
   }
 }