Relanding this with fixes for the unit test failures which required addition of some more plumbing …

ui/views/controls/webview/webview_unittest.cc

+// Copyright 2014 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 "ui/views/controls/webview/webview.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/web_contents/web_contents_impl.h"
+#include "content/public/browser/web_contents_observer.h"
+#include "content/public/test/test_browser_context.h"
+#include "content/public/test/test_browser_thread.h"
+#include "content/public/test/web_contents_tester.h"
+#include "content/test/test_content_browser_client.h"
+#include "ui/aura/window.h"
+#include "ui/views/test/test_views_delegate.h"
+#include "ui/views/test/widget_test.h"
+
+namespace {
+
+// Provides functionality to create a test WebContents.
+class WebViewTestViewsDelegate : public views::TestViewsDelegate {
+ public:
+  WebViewTestViewsDelegate() {}
+  virtual ~WebViewTestViewsDelegate() {}
+
+  // Overriden from TestViewsDelegate.
+  virtual content::WebContents* CreateWebContents(
+      content::BrowserContext* browser_context,
+      content::SiteInstance* site_instance) OVERRIDE {
+    return content::WebContentsTester::CreateTestWebContents(browser_context,
+                                                             site_instance);
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WebViewTestViewsDelegate);
+};
+
+// Provides functionality to test a WebView.
+class WebViewUnitTest : public views::test::WidgetTest {
+ public:
+  WebViewUnitTest()
+      : ui_thread_(content::BrowserThread::UI, base::MessageLoop::current()),
+        file_blocking_thread_(content::BrowserThread::FILE_USER_BLOCKING,
+                              base::MessageLoop::current()),
+        io_thread_(content::BrowserThread::IO, base::MessageLoop::current()) {}
+
+  virtual ~WebViewUnitTest() {}
+
+  virtual void SetUp() OVERRIDE {
+    // The ViewsDelegate is deleted when the ViewsTestBase class is torn down.
+    WidgetTest::set_views_delegate(new WebViewTestViewsDelegate);
+    browser_context_.reset(new content::TestBrowserContext);
+    WidgetTest::SetUp();
+    // Set the test content browser client to avoid pulling in needless
+    // dependencies from content.
+    SetBrowserClientForTesting(&test_browser_client_);
+  }
+
+  virtual void TearDown() OVERRIDE {
+    browser_context_.reset(NULL);
+    // Flush the message loop to execute pending relase tasks as this would
+    // upset ASAN and Valgrind.
+    RunPendingMessages();
+    WidgetTest::TearDown();
+  }
+
+ protected:
+  content::BrowserContext* browser_context() { return browser_context_.get(); }
+
+ private:
+  content::TestBrowserThread ui_thread_;
+  content::TestBrowserThread file_blocking_thread_;
+  content::TestBrowserThread io_thread_;
+  scoped_ptr<content::TestBrowserContext> browser_context_;
+  scoped_ptr<WebViewTestViewsDelegate> views_delegate_;
+  content::TestContentBrowserClient test_browser_client_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewUnitTest);
+};
+
+// Provides functionaity to observe events on a WebContents like WasShown/
+// WasHidden/WebContentsDestroyed.
+class WebViewTestWebContentsObserver : public content::WebContentsObserver {
+ public:
+  WebViewTestWebContentsObserver(content::WebContents* web_contents)
+      : web_contents_(static_cast<content::WebContentsImpl*>(web_contents)),
+        was_shown_(false),
+        shown_count_(0),
+        hidden_count_(0) {
+    content::WebContentsObserver::Observe(web_contents);
+  }
+
+  virtual ~WebViewTestWebContentsObserver() {
+    if (web_contents_)
+      content::WebContentsObserver::Observe(NULL);
+  }
+
+  virtual void WebContentsDestroyed() OVERRIDE {
+    DCHECK(web_contents_);
+    content::WebContentsObserver::Observe(NULL);
+    web_contents_ = NULL;
+  }
+
+  virtual void WasShown() OVERRIDE {
+    was_shown_ = true;
+    ++shown_count_;
+  }
+
+  virtual void WasHidden() OVERRIDE {
+    was_shown_ = false;
+    ++hidden_count_;
+  }
+
+  bool was_shown() const { return was_shown_; }
+
+  int shown_count() const { return shown_count_; }
+
+  int hidden_count() const { return hidden_count_; }
+
+ private:
+  content::WebContentsImpl* web_contents_;
+  bool was_shown_;
+  int32 shown_count_;
+  int32 hidden_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebViewTestWebContentsObserver);
+};
+
+// Tests that attaching and detaching a WebContents to a WebView makes the
+// WebContents visible and hidden respectively.
+TEST_F(WebViewUnitTest, TestWebViewAttachDetachWebContents) {
+  // Create a top level widget and a webview as its content.
+  views::Widget* widget = CreateTopLevelFramelessPlatformWidget();
+  widget->SetBounds(gfx::Rect(0, 10, 100, 100));
+  views::WebView* webview = new views::WebView(browser_context());
+  widget->SetContentsView(webview);
+  widget->Show();
+
+  // Case 1: Create a new WebContents and set it in the webview via
+  // SetWebContents. This should make the WebContents visible.
+  content::WebContents::CreateParams params(browser_context());
+  scoped_ptr<content::WebContents> web_contents1(
+      content::WebContents::Create(params));
+  WebViewTestWebContentsObserver observer1(web_contents1.get());
+  EXPECT_FALSE(observer1.was_shown());
+
+  webview->SetWebContents(web_contents1.get());
+  EXPECT_TRUE(observer1.was_shown());
+  EXPECT_TRUE(web_contents1->GetNativeView()->IsVisible());
+  EXPECT_EQ(observer1.shown_count(), 1);
+  EXPECT_EQ(observer1.hidden_count(), 0);
+
+  // Case 2: Create another WebContents and replace the current WebContents
+  // via SetWebContents(). This should hide the current WebContents and show
+  // the new one.
+  content::WebContents::CreateParams params2(browser_context());
+  scoped_ptr<content::WebContents> web_contents2(
+      content::WebContents::Create(params2));
+  WebViewTestWebContentsObserver observer2(web_contents2.get());
+  EXPECT_FALSE(observer2.was_shown());
+
+  // Setting the new WebContents should hide the existing one.
+  webview->SetWebContents(web_contents2.get());
+  EXPECT_FALSE(observer1.was_shown());
+  EXPECT_TRUE(observer2.was_shown());
+
+  // WebContents1 should not get stray show calls when WebContents2 is set.
+  EXPECT_EQ(observer1.shown_count(), 1);
+  EXPECT_EQ(observer1.hidden_count(), 1);
+  EXPECT_EQ(observer2.shown_count(), 1);
+  EXPECT_EQ(observer2.hidden_count(), 0);
+
+  widget->Close();
+  RunPendingMessages();
+}
+
+}  // namespace