Add support for entering/exiting HTML fullscreen from OOPIFs.

chrome/browser/site_per_process_interactive_browsertest.cc

Index: chrome/browser/site_per_process_interactive_browsertest.cc
diff --git a/chrome/browser/site_per_process_interactive_browsertest.cc b/chrome/browser/site_per_process_interactive_browsertest.cc
index 17fdbe539cda066e20a09ac4add980c8cb00a292..cc07a494c58115b47ba41e69e668c47475e8496d 100644
--- a/chrome/browser/site_per_process_interactive_browsertest.cc
+++ b/chrome/browser/site_per_process_interactive_browsertest.cc
@@ -3,17 +3,24 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
+#include "base/strings/string_number_conversions.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_window.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
 #include "chrome/test/base/in_process_browser_test.h"
+#include "chrome/test/base/interactive_test_utils.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "content/public/browser/render_frame_host.h"
+#include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/content_browser_test_utils.h"
+#include "content/public/test/test_navigation_observer.h"
 #include "content/public/test/test_utils.h"
 #include "net/dns/mock_host_resolver.h"
 #include "net/test/embedded_test_server/embedded_test_server.h"
+#include "ui/display/display.h"
+#include "ui/display/screen.h"
 #include "url/gurl.h"
 
 class SitePerProcessInteractiveBrowserTest : public InProcessBrowserTest {
@@ -34,6 +41,15 @@ class SitePerProcessInteractiveBrowserTest : public InProcessBrowserTest {
     ASSERT_TRUE(embedded_test_server()->Start());
   }
 
+  gfx::Size GetScreenSize() {
+    content::WebContents* web_contents =
+        browser()->tab_strip_model()->GetActiveWebContents();
+    const display::Display display =
+        display::Screen::GetScreen()->GetDisplayNearestWindow(
+            web_contents->GetRenderWidgetHostView()->GetNativeView());
+    return display.bounds().size();
+  }
+
  private:
   DISALLOW_COPY_AND_ASSIGN(SitePerProcessInteractiveBrowserTest);
 };
@@ -232,3 +248,452 @@ IN_PROC_BROWSER_TEST_F(SitePerProcessInteractiveBrowserTest,
   EXPECT_EQ(main_frame, web_contents->GetFocusedFrame());
 }
 
+namespace {
+
+// Helper to retrieve the frame's (window.innerWidth, window.innerHeight).
+gfx::Size GetFrameSize(content::RenderFrameHost* frame) {
+  int width = 0;
+  EXPECT_TRUE(ExecuteScriptAndExtractInt(
+      frame, "domAutomationController.send(window.innerWidth);", &width));
+
+  int height = 0;
+  EXPECT_TRUE(ExecuteScriptAndExtractInt(
+      frame, "domAutomationController.send(window.innerHeight);", &height));
+
+  return gfx::Size(width, height);
+}
+
+// Helper to check |frame|'s document.webkitFullscreenElement and return its ID
+// if it's defined (which is the case when |frame| is in fullscreen mode), or
+// "none" otherwise.
+std::string GetFullscreenElementId(content::RenderFrameHost* frame) {
+  std::string fullscreen_element;
+  EXPECT_TRUE(ExecuteScriptAndExtractString(
+      frame,
+      "domAutomationController.send("
+      "    document.webkitFullscreenElement ? "
+      "        document.webkitFullscreenElement.id : 'none')",
+      &fullscreen_element));
+  return fullscreen_element;
+}
+
+// Helper to check if an element with ID |element_id| has the
+// :-webkit-full-screen style.
+bool ElementHasFullscreenStyle(content::RenderFrameHost* frame,
+                               const std::string& element_id) {
+  bool has_style = false;
+  std::string script = base::StringPrintf(
+      "domAutomationController.send("
+      "    document.querySelectorAll('#%s:-webkit-full-screen').length == 1)",
+      element_id.c_str());
+  EXPECT_TRUE(ExecuteScriptAndExtractBool(frame, script, &has_style));
+  return has_style;
+}
+
+// Helper to check if an element with ID |element_id| has the
+// :-webkit-full-screen-ancestor style.
+bool ElementHasFullscreenAncestorStyle(content::RenderFrameHost* host,
+                                       const std::string& element_id) {
+  bool has_style = false;
+  std::string script = base::StringPrintf(
+      "domAutomationController.send("
+      "    document.querySelectorAll("
+      "        '#%s:-webkit-full-screen-ancestor').length == 1)",
+      element_id.c_str());
+  EXPECT_TRUE(ExecuteScriptAndExtractBool(host, script, &has_style));
+  return has_style;
+}
+
+// Set the allowFullscreen attribute on the <iframe> element identified by
+// |frame_id|.
+void SetAllowFullscreenForFrame(content::RenderFrameHost* host,
+                                const std::string& frame_id) {
+  EXPECT_TRUE(ExecuteScript(
+      host, base::StringPrintf(
+                "document.getElementById('%s').allowFullscreen = true;",
+                frame_id.c_str())));
+}
+
+// Add a listener that will send back a message whenever the (prefixed)
+// fullscreenchange event fires.  The message will be "fullscreenchange",
+// followed by a space and the provided |id|.
+void AddFullscreenChangeListener(content::RenderFrameHost* frame,
+                                 const std::string& id) {
+  std::string script = base::StringPrintf(
+      "document.addEventListener('webkitfullscreenchange', function() {"
+      "    domAutomationController.setAutomationId(0);"
+      "    domAutomationController.send('fullscreenchange %s');});",
+      id.c_str());
+  EXPECT_TRUE(ExecuteScript(frame, script));
+}
+
+// Helper to add a listener that will send back a "resize" message when the
+// target |frame| is resized to |expected_size|.
+void AddResizeListener(content::RenderFrameHost* frame,
+                       const gfx::Size& expected_size) {
+  std::string script =
+      base::StringPrintf("addResizeListener(%d, %d);",
+                         expected_size.width(), expected_size.height());
+  EXPECT_TRUE(ExecuteScript(frame, script));
+}
+
+// Helper to wait for a toggle fullscreen operation to complete in all affected
+// frames.  This means waiting for:
+// 1. All fullscreenchange events with id's matching the list in
+//    |expected_fullscreen_event_ids|.  Typically the list will correspond to
+//    events from the actual fullscreen element and all of its ancestor
+//    <iframe> elements.
+// 2. A resize event.  This will verify that the frame containing the
+//    fullscreen element is properly resized.  This assumes that the expected
+//    size is already registered via AddResizeListener().
+void WaitForMultipleFullscreenEvents(
+    const std::set<std::string>& expected_fullscreen_event_ids,
+    content::DOMMessageQueue& queue) {
+  std::set<std::string> remaining_events(expected_fullscreen_event_ids);
+  bool resize_validated = false;
+  std::string response;
+  while (queue.WaitForMessage(&response)) {
+    base::TrimString(response, "\"", &response);
+    std::vector<std::string> response_params = base::SplitString(
+        response, " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
+    if (response_params[0] == "fullscreenchange") {
+      EXPECT_TRUE(ContainsKey(remaining_events, response_params[1]));
+      remaining_events.erase(response_params[1]);
+    } else if (response_params[0] == "resize") {
+      resize_validated = true;
+    }
+    if (remaining_events.empty() && resize_validated)
+      break;
+  }
+}
+
+}  // namespace
+
+// Check that an element in a cross-process subframe can enter and exit
+// fullscreen.  The test will verify that:
+// - the subframe is properly resized
+// - the WebContents properly enters/exits fullscreen.
+// - document.webkitFullscreenElement is correctly updated in both frames.
+// - fullscreenchange events fire in both frames.
+// - fullscreen CSS is applied correctly in both frames.
+IN_PROC_BROWSER_TEST_F(SitePerProcessInteractiveBrowserTest,
+                       FullscreenElementInSubframe) {
+  // Start on a page with one subframe (id "child-0") that has
+  // "allowfullscreen" enabled.
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/page_with_allowfullscreen_frame.html"));
+  ui_test_utils::NavigateToURL(browser(), main_url);
+  content::WebContents* web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  // Navigate the subframe cross-site to a page with a fullscreenable <div>.
+  GURL frame_url(
+      embedded_test_server()->GetURL("b.com", "/fullscreen_frame.html"));
+  EXPECT_TRUE(NavigateIframeToURL(web_contents, "child-0", frame_url));
+
+  content::RenderFrameHost* main_frame = web_contents->GetMainFrame();
+  content::RenderFrameHost* child = ChildFrameAt(main_frame, 0);
+  gfx::Size original_child_size = GetFrameSize(child);
+
+  // Fullscreen the <div> inside the cross-site child frame.  Wait until:
+  // (1) the fullscreenchange events in main frame and child send a response,
+  // (2) the child frame is resized to fill the whole screen.
+  AddFullscreenChangeListener(main_frame, "main_frame");
+  AddFullscreenChangeListener(child, "child");
+  std::set<std::string> expected_events = {"main_frame", "child"};
+  AddResizeListener(child, GetScreenSize());
+  {
+    content::DOMMessageQueue queue;
+    EXPECT_TRUE(ExecuteScript(child, "activateFullscreen()"));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  // Verify that the browser has entered fullscreen for the current tab.
+  EXPECT_TRUE(browser()->window()->IsFullscreen());
+  EXPECT_TRUE(browser()->exclusive_access_manager()
+                       ->fullscreen_controller()
+                       ->IsFullscreenForTabOrPending(web_contents));
+
+  // Verify that the <div> has fullscreen style (:-webkit-full-screen) in the
+  // subframe.
+  EXPECT_TRUE(ElementHasFullscreenStyle(child, "fullscreen-div"));
+
+  // Verify that the main frame has applied proper fullscreen styles to the
+  // <iframe> element (:-webkit-full-screen and :-webkit-full-screen-ancestor).
+  // This is what causes the <iframe> to stretch and fill the whole viewport.
+  EXPECT_TRUE(ElementHasFullscreenStyle(main_frame, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenAncestorStyle(main_frame, "child-0"));
+
+  // Check document.webkitFullscreenElement.  For main frame, it should point
+  // to the subframe, and for subframe, it should point to the fullscreened
+  // <div>.
+  EXPECT_EQ("child-0", GetFullscreenElementId(main_frame));
+  EXPECT_EQ("fullscreen-div", GetFullscreenElementId(child));
+
+  // Now exit fullscreen from the subframe.  Wait for two fullscreenchange
+  // events from both frames, and also for the child to be resized to its
+  // original size.
+  AddResizeListener(child, original_child_size);
+  {
+    content::DOMMessageQueue queue;
+    EXPECT_TRUE(ExecuteScript(child, "exitFullscreen()"));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  EXPECT_FALSE(browser()->window()->IsFullscreen());
+
+  // Verify that the fullscreen styles were removed from the <div> and its
+  // container <iframe>.
+  EXPECT_FALSE(ElementHasFullscreenStyle(child, "fullscreen-div"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(main_frame, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenAncestorStyle(main_frame, "child-0"));
+
+  // Check that both frames cleared their document.webkitFullscreenElement.
+  EXPECT_EQ("none", GetFullscreenElementId(main_frame));
+  EXPECT_EQ("none", GetFullscreenElementId(child));
+}
+
+// Check that on a page with A-embed-B-embed-A frame hierarchy, an element in
+// the bottom frame can enter and exit fullscreen.
+//
+// TODO(alexmos): For now, the test will verify sizing and fullscreen CSS
+// styles, but additional refactoring of Blink's Fullscreen class is required
+// to fully handle fullscreenchange events and webkitFullscreenElement in the
+// main frame.
+IN_PROC_BROWSER_TEST_F(SitePerProcessInteractiveBrowserTest,
+                       FullscreenElementInABA) {
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/cross_site_iframe_factory.html?a(b(a))"));
+  ui_test_utils::NavigateToURL(browser(), main_url);
+  content::WebContents* web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  content::RenderFrameHost* main_frame = web_contents->GetMainFrame();
+  content::RenderFrameHost* child = ChildFrameAt(main_frame, 0);
+  content::RenderFrameHost* grandchild = ChildFrameAt(child, 0);
+
+  // Navigate the bottom frame to a page that has a fullscreenable <div>.
+  content::TestNavigationObserver observer(web_contents);
+  EXPECT_TRUE(
+      ExecuteScript(grandchild, "location.href = '/fullscreen_frame.html'"));
+  observer.Wait();
+  EXPECT_EQ(embedded_test_server()->GetURL("a.com", "/fullscreen_frame.html"),
+            grandchild->GetLastCommittedURL());
+
+  // Add allowFullscreen attribute to both <iframe> elements.
+  SetAllowFullscreenForFrame(main_frame, "child-0");
+  SetAllowFullscreenForFrame(child, "child-0");
+
+  // Make fullscreenchange events in all three frames send a message.
+  AddFullscreenChangeListener(main_frame, "main_frame");
+  AddFullscreenChangeListener(child, "child");
+  AddFullscreenChangeListener(grandchild, "grandchild");
+
+  // Add a resize event handler that will send a message when the grandchild
+  // frame is resized to the screen size.  Also save its original size.
+  AddResizeListener(grandchild, GetScreenSize());
+  gfx::Size original_grandchild_size = GetFrameSize(grandchild);
+
+  // Fullscreen a <div> inside the bottom subframe.  This will block until
+  // (1) the fullscreenchange events in all frames send a response, and
+  // (2) the frame is resized to fill the whole screen.
+  //
+  // TODO(alexmos): Also wait for "main_frame" once
+  // blink::Fullscreen::requestFullscreen() and exitFullscreen() are fixed to
+  // process all local ancestors.
+  std::set<std::string> expected_events = {"child", "grandchild"};
+  {
+    content::DOMMessageQueue queue;
+    EXPECT_TRUE(ExecuteScript(grandchild, "activateFullscreen()"));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  // Verify that the browser has entered fullscreen for the current tab.
+  EXPECT_TRUE(browser()->window()->IsFullscreen());
+  EXPECT_TRUE(browser()->exclusive_access_manager()
+                       ->fullscreen_controller()
+                       ->IsFullscreenForTabOrPending(web_contents));
+
+  // Verify that the <div> has fullscreen style in the bottom frame, and that
+  // the proper <iframe> elements have fullscreen style in its ancestor frames.
+  EXPECT_TRUE(ElementHasFullscreenStyle(grandchild, "fullscreen-div"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(child, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenAncestorStyle(child, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(main_frame, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenAncestorStyle(main_frame, "child-0"));
+
+  // Check document.webkitFullscreenElement in all frames.
+  EXPECT_EQ("child-0", GetFullscreenElementId(child));
+  EXPECT_EQ("fullscreen-div", GetFullscreenElementId(grandchild));
+  // TODO(alexmos): Also check that |main_frame|'s webkitFullscreenElement is
+  // "child-0" once blink::Fullscreen::requestFullscreen() is fixed to handle
+  // all local ancestors.
+
+  // Now exit fullscreen from the subframe.
+  AddResizeListener(grandchild, original_grandchild_size);
+  {
+    content::DOMMessageQueue queue;
+    EXPECT_TRUE(ExecuteScript(grandchild, "exitFullscreen()"));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  EXPECT_FALSE(browser()->window()->IsFullscreen());
+
+  // Verify that the fullscreen styles were removed from the <div> and its
+  // container <iframe>'s.
+  EXPECT_FALSE(ElementHasFullscreenStyle(grandchild, "fullscreen-div"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(child, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenAncestorStyle(child, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(main_frame, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenAncestorStyle(main_frame, "child-0"));
+
+  // Check that document.webkitFullscreenElement was cleared in all three
+  // frames.
+  EXPECT_EQ("none", GetFullscreenElementId(main_frame));
+  EXPECT_EQ("none", GetFullscreenElementId(child));
+  EXPECT_EQ("none", GetFullscreenElementId(grandchild));
+}
+
+// Check that fullscreen works on a more complex page hierarchy with multiple
+// local and remote ancestors.  The test uses this frame tree:
+//
+//             A (a_top)
+//             |
+//             A (a_bottom)
+//            / \   .
+// (b_first) B   B (b_second)
+//               |
+//               C (c_top)
+//               |
+//               C (c_middle) <- fullscreen target
+//               |
+//               C (c_bottom)
+//
+// The c_middle frame will trigger fullscreen for its <div> element.  The test
+// verifies that its ancestor chain is properly updated for fullscreen, and
+// that the b_first node that's not on the chain is not affected.
+//
+// The test also exits fullscreen by simulating pressing ESC rather than using
+// document.webkitExitFullscreen(), which tests the browser-initiated
+// fullscreen exit path.
+IN_PROC_BROWSER_TEST_F(SitePerProcessInteractiveBrowserTest,
+                       FullscreenElementInMultipleSubframes) {
+  GURL main_url(embedded_test_server()->GetURL(
+      "a.com", "/cross_site_iframe_factory.html?a(a(b,b(c(c))))"));
+  ui_test_utils::NavigateToURL(browser(), main_url);
+  content::WebContents* web_contents =
+      browser()->tab_strip_model()->GetActiveWebContents();
+
+  content::RenderFrameHost* a_top = web_contents->GetMainFrame();
+  content::RenderFrameHost* a_bottom = ChildFrameAt(a_top, 0);
+  content::RenderFrameHost* b_first = ChildFrameAt(a_bottom, 0);
+  content::RenderFrameHost* b_second = ChildFrameAt(a_bottom, 1);
+  content::RenderFrameHost* c_top = ChildFrameAt(b_second, 0);
+  content::RenderFrameHost* c_middle = ChildFrameAt(c_top, 0);
+
+  // Allow fullscreen in all iframes descending to |c_middle|.  This relies on
+  // IDs that cross_site_iframe_factory assigns to child frames.
+  SetAllowFullscreenForFrame(a_top, "child-0");
+  SetAllowFullscreenForFrame(a_bottom, "child-1");
+  SetAllowFullscreenForFrame(b_second, "child-0");
+  SetAllowFullscreenForFrame(c_top, "child-0");
+
+  // Navigate |c_middle| to a page that has a fullscreenable <div> and another
+  // frame.
+  content::TestNavigationObserver observer(web_contents);
+  EXPECT_TRUE(
+      ExecuteScript(c_middle, "location.href = '/fullscreen_frame.html'"));
+  observer.Wait();
+  EXPECT_EQ(embedded_test_server()->GetURL("c.com", "/fullscreen_frame.html"),
+            c_middle->GetLastCommittedURL());
+  content::RenderFrameHost* c_bottom = ChildFrameAt(c_middle, 0);
+
+  // Save the size of the frame to be fullscreened.
+  gfx::Size c_middle_original_size = GetFrameSize(c_middle);
+
+  // Add fullscreenchange and resize event handlers to all frames.
+  AddFullscreenChangeListener(a_top, "a_top");
+  AddFullscreenChangeListener(a_bottom, "a_bottom");
+  AddFullscreenChangeListener(b_first, "b_first");
+  AddFullscreenChangeListener(b_second, "b_second");
+  AddFullscreenChangeListener(c_top, "c_top");
+  AddFullscreenChangeListener(c_middle, "c_middle");
+  AddFullscreenChangeListener(c_bottom, "c_bottom");
+  AddResizeListener(c_middle, GetScreenSize());
+
+  // Note that expected fullscreenchange events do NOT include |b_first| and
+  // |c_bottom|, which aren't on the ancestor chain of |c_middle|.
+  // WaitForMultipleFullscreenEvents() below will fail if it hears an
+  // unexpected fullscreenchange from one of these frames.
+  std::set<std::string> expected_events = {"a_top", "a_bottom", "b_second",
+                                           "c_top", "c_middle"};
+
+  // Fullscreen a <div> inside |c_middle|.  Block until (1) the
+  // fullscreenchange events in |c_middle| and all its ancestors send a
+  // response, and (2) |c_middle| is resized to fill the whole screen.
+  {
+    content::DOMMessageQueue queue;
+    EXPECT_TRUE(ExecuteScript(c_middle, "activateFullscreen()"));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  // Verify that the browser has entered fullscreen for the current tab.
+  EXPECT_TRUE(browser()->window()->IsFullscreen());
+  EXPECT_TRUE(browser()->exclusive_access_manager()
+                       ->fullscreen_controller()
+                       ->IsFullscreenForTabOrPending(web_contents));
+
+  // Check document.webkitFullscreenElement.  It should point to corresponding
+  // <iframe> element IDs on |c_middle|'s ancestor chain, and it should be null
+  // in b_first and c_bottom.
+  EXPECT_EQ("child-0", GetFullscreenElementId(a_top));
+  EXPECT_EQ("child-1", GetFullscreenElementId(a_bottom));
+  EXPECT_EQ("child-0", GetFullscreenElementId(b_second));
+  EXPECT_EQ("child-0", GetFullscreenElementId(c_top));
+  EXPECT_EQ("fullscreen-div", GetFullscreenElementId(c_middle));
+  EXPECT_EQ("none", GetFullscreenElementId(b_first));
+  EXPECT_EQ("none", GetFullscreenElementId(c_bottom));
+
+  // Verify that the fullscreen element and all <iframe> elements on its
+  // ancestor chain have fullscreen style, but other frames do not.
+  EXPECT_TRUE(ElementHasFullscreenStyle(a_top, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(a_bottom, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(a_bottom, "child-1"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(b_second, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(c_top, "child-0"));
+  EXPECT_TRUE(ElementHasFullscreenStyle(c_middle, "fullscreen-div"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(c_middle, "child-0"));
+
+  // Now exit fullscreen by pressing escape.  Wait for all fullscreenchange
+  // events fired for fullscreen exit and verify that the bottom frame was
+  // resized back to its original size.
+  AddResizeListener(c_middle, c_middle_original_size);
+  {
+    content::DOMMessageQueue queue;
+    ASSERT_TRUE(ui_test_utils::SendKeyPressSync(browser(), ui::VKEY_ESCAPE,
+                                                false, false, false, false));
+    WaitForMultipleFullscreenEvents(expected_events, queue);
+  }
+
+  EXPECT_FALSE(browser()->window()->IsFullscreen());
+
+  // Check that document.webkitFullscreenElement has been cleared in all
+  // frames.
+  EXPECT_EQ("none", GetFullscreenElementId(a_top));
+  EXPECT_EQ("none", GetFullscreenElementId(a_bottom));
+  EXPECT_EQ("none", GetFullscreenElementId(b_first));
+  EXPECT_EQ("none", GetFullscreenElementId(b_second));
+  EXPECT_EQ("none", GetFullscreenElementId(c_top));
+  EXPECT_EQ("none", GetFullscreenElementId(c_middle));
+  EXPECT_EQ("none", GetFullscreenElementId(c_bottom));
+
+  // Verify that all fullscreen styles have been cleared.
+  EXPECT_FALSE(ElementHasFullscreenStyle(a_top, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(a_bottom, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(a_bottom, "child-1"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(b_second, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(c_top, "child-0"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(c_middle, "fullscreen-div"));
+  EXPECT_FALSE(ElementHasFullscreenStyle(c_middle, "child-0"));
+}
+