Don't center screen magnification on empty focus rectangle

ash/magnifier/magnification_controller_unittest.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/magnifier/magnification_controller.h"
 
 #include "ash/display/display_manager.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "base/strings/stringprintf.h"
@@ skipping 248 matching lines @@
   generator.MoveMouseToInHost(gfx::Point(400, 300));
   EXPECT_EQ("400,300", CurrentPointOfInterest());
 
   GetMagnificationController()->SetEnabled(true);
   EXPECT_EQ("400,300", CurrentPointOfInterest());
 
   generator.MoveMouseToInHost(gfx::Point(500, 400));
   EXPECT_EQ("450,350", CurrentPointOfInterest());
 }
 
+TEST_F(MagnificationControllerTest, FollowFocusChanged) {
+  // Enables magnifier and confirm the viewport is at center.
+  GetMagnificationController()->SetEnabled(true);
+  EXPECT_EQ(2.0f, GetMagnificationController()->GetScale());
+  EXPECT_EQ("200,150 400x300", GetViewport().ToString());
+
+  // Don't move viewport when focusing edit box.
+  GetMagnificationController()->HandleFocusedNodeChanged(
+      true, gfx::Rect(0, 0, 10, 10));
+  EXPECT_EQ("200,150 400x300", GetViewport().ToString());
+
+  // Move viewport to element in upper left.
+  GetMagnificationController()->HandleFocusedNodeChanged(
+      false, gfx::Rect(0, 0, 10, 10));
+  EXPECT_EQ("0,0 400x300", GetViewport().ToString());
+
+  // Move viewport to element in lower right.
+  GetMagnificationController()->HandleFocusedNodeChanged(
+      false, gfx::Rect(790, 590, 10, 10));
+  EXPECT_EQ("400,300 400x300", GetViewport().ToString());
+
+  // Don't follow focus onto empty rectangle.
+  GetMagnificationController()->HandleFocusedNodeChanged(
+      false, gfx::Rect(0, 0, 0, 0));
+  EXPECT_EQ("400,300 400x300", GetViewport().ToString());
+}
+
 TEST_F(MagnificationControllerTest, PanWindow2xLeftToRight) {
   const aura::Env* env = aura::Env::GetInstance();
   ui::test::EventGenerator generator(Shell::GetPrimaryRootWindow());
 
   generator.MoveMouseToInHost(gfx::Point(0, 0));
   EXPECT_EQ(1.f, GetMagnificationController()->GetScale());
   EXPECT_EQ("0,0 800x600", GetViewport().ToString());
   EXPECT_EQ("0,0", env->last_mouse_location().ToString());
 
   // Enables magnifier and confirm the viewport is at center.
@@ skipping 414 matching lines @@
   UpdateDisplay("500x500");
   EXPECT_EQ("0,0 500x500", screen->GetPrimaryDisplay().bounds().ToString());
   EXPECT_EQ(2.0f, GetMagnificationController()->GetScale());
 
   GetMagnificationController()->SetEnabled(false);
   EXPECT_EQ("0,0 500x500", screen->GetPrimaryDisplay().bounds().ToString());
   EXPECT_EQ(1.0f, GetMagnificationController()->GetScale());
 }
 
 }  // namespace ash