Correctly sets the security origin for the IME window.

chrome/browser/ui/views/ime/ime_window_browsertest.cc

 // Copyright 2016 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 "base/run_loop.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/ime/ime_native_window.h"
 #include "chrome/browser/ui/ime/ime_window.h"
 #include "chrome/browser/ui/ime/ime_window_observer.h"
+#include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/test/base/in_process_browser_test.h"
 #include "ui/views/widget/widget.h"
 
 namespace ui {
 namespace test {
 
 class ImeWindowBrowserTest : public InProcessBrowserTest,
                              public ImeWindowObserver {
  public:
   ImeWindowBrowserTest() : ime_window_(nullptr) {}
@@ skipping 13 matching lines @@
     message_loop_runner_->Quit();
   }
 
   void WaitForWindowClosing() {
     message_loop_runner_.reset(new base::RunLoop);
     message_loop_runner_->Run();
   }
 
   void CreateImeWindow(const gfx::Rect& bounds, bool follow_cursor) {
     ime_window_ = new ImeWindow(
-        browser()->profile(), nullptr, "about:blank",
+        browser()->profile(), nullptr,
+        browser()->tab_strip_model()->GetActiveWebContents()->GetMainFrame(),

[Devlin, 2016/03/02 18:05:11]

Does this RFH make sense as the opener?

[Shu Chen, 2016/03/03 01:33:32]

Done. I've made it nullptr.

+        "about:blank",
         follow_cursor ? ImeWindow::FOLLOW_CURSOR : ImeWindow::NORMAL, bounds);
     ime_window_->AddObserver(this);
     EXPECT_FALSE(ime_window_->ime_native_window()->IsVisible());
     ime_window_->Show();
     EXPECT_TRUE(ime_window_->ime_native_window()->IsVisible());
   }
 
   void VerifyImeWindow(const gfx::Rect& expected_bounds) {
     EXPECT_EQ(expected_bounds,
               ime_window_->ime_native_window()->GetBounds());
@@ skipping 23 matching lines @@
   gfx::Rect expected_bounds(100, 200, 100, 100);
   CreateImeWindow(expected_bounds, true);
   ime_window_->FollowCursor(gfx::Rect(10, 20, 1, 10));
   expected_bounds.set_x(10);  // cursor left.
   expected_bounds.set_y(33);  // cursor top + cursor height + margin(3).
   VerifyImeWindow(expected_bounds);
 }
 
 }  // namespace test
 }  // namespace ui