Make gfx::Rect class operations consistently mutate the class they are called on.

ash/launcher/launcher_view_unittest.cc

 // Copyright (c) 2012 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/launcher/launcher_view.h"
 
 #include <algorithm>
 #include <vector>
 
 #include "ash/launcher/launcher.h"
@@ skipping 627 matching lines @@
 
   // The tooltip should not hide on the app-list button.
   views::View* app_list_button = launcher_view_->GetAppListButtonView();
   EXPECT_FALSE(launcher_view_->ShouldHideTooltip(
       app_list_button->GetMirroredBounds().CenterPoint()));
 
   // The tooltip shouldn't hide if the mouse is in the gap between two buttons.
   gfx::Rect app_button_rect = GetButtonByID(app_button_id)->GetMirroredBounds();
   gfx::Rect tab_button_rect = GetButtonByID(tab_button_id)->GetMirroredBounds();
   ASSERT_FALSE(app_button_rect.Intersects(tab_button_rect));
-  EXPECT_FALSE(launcher_view_->ShouldHideTooltip(
-      app_button_rect.Union(tab_button_rect).CenterPoint()));
+  gfx::Rect union_rect = app_button_rect;
+  union_rect.Union(tab_button_rect);
+  EXPECT_FALSE(launcher_view_->ShouldHideTooltip(union_rect.CenterPoint()));
 
   // The tooltip should hide if it's outside of all buttons.
   gfx::Rect all_area;
   for (int i = 0; i < test_api_->GetButtonCount(); i++) {
     internal::LauncherButton* button = test_api_->GetButton(i);
     if (!button)
       continue;
 
-    all_area = all_area.Union(button->GetMirroredBounds());
+    all_area.Union(button->GetMirroredBounds());
   }
-  all_area = all_area.Union(
-      launcher_view_->GetAppListButtonView()->GetMirroredBounds());
+  all_area.Union(launcher_view_->GetAppListButtonView()->GetMirroredBounds());
   EXPECT_FALSE(launcher_view_->ShouldHideTooltip(all_area.origin()));
   EXPECT_FALSE(launcher_view_->ShouldHideTooltip(
       gfx::Point(all_area.right() - 1, all_area.bottom() - 1)));
   EXPECT_TRUE(launcher_view_->ShouldHideTooltip(
       gfx::Point(all_area.right(), all_area.y())));
   EXPECT_TRUE(launcher_view_->ShouldHideTooltip(
       gfx::Point(all_area.x() - 1, all_area.y())));
   EXPECT_TRUE(launcher_view_->ShouldHideTooltip(
       gfx::Point(all_area.x(), all_area.y() - 1)));
   EXPECT_TRUE(launcher_view_->ShouldHideTooltip(
@@ skipping 50 matching lines @@
   const int app_list_button_index = test_api_->GetButtonCount() - 1;
   const gfx::Rect& app_list_ideal_bounds =
       test_api_->GetIdealBoundsByIndex(app_list_button_index);
   const gfx::Rect& app_list_bounds =
       test_api_->GetBoundsByIndex(app_list_button_index);
   EXPECT_EQ(app_list_bounds, app_list_ideal_bounds);
 }
 
 }  // namespace test
 }  // namespace ash