weblayer: avoid calling FullscreenDelegate in certain scenarios

While the typical case is EnterFullscreenModeForTab is not called
multiple times in a row, there may be some corner cases with oopif
that result in it being called consecutively. This ensure the
delegate is only notified once.

BUG=1142101
TEST=FullscreenBrowserTest.DelegateNotCalledMoreThanOnce

Change-Id: Ifa094e53b714f78fe61a0d5dd46a33f08c436e30
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2630726
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843788}

weblayer/browser/fullscreen_browsertest.cc

@@ -92,4 +92,34 @@ IN_PROC_BROWSER_TEST_F(FullscreenBrowserTest, NoExitForBackgroundTab) {
   tab->SetFullscreenDelegate(nullptr);
 }
 
+IN_PROC_BROWSER_TEST_F(FullscreenBrowserTest, DelegateNotCalledMoreThanOnce) {
+  EXPECT_TRUE(embedded_test_server()->Start());
+
+  // The tab needs to be made active as fullscreen requests for inactive tabs
+  // are ignored.
+  TabImpl* tab = static_cast<TabImpl*>(shell()->tab());
+  tab->GetBrowser()->SetActiveTab(tab);
+
+  FullscreenDelegateImpl fullscreen_delegate;
+  tab->SetFullscreenDelegate(&fullscreen_delegate);
+  static_cast<content::WebContentsDelegate*>(tab)->EnterFullscreenModeForTab(
+      nullptr, blink::mojom::FullscreenOptions());
+  EXPECT_TRUE(static_cast<content::WebContentsDelegate*>(tab)
+                  ->IsFullscreenForTabOrPending(nullptr));
+  EXPECT_TRUE(fullscreen_delegate.got_enter());
+  EXPECT_FALSE(fullscreen_delegate.got_exit());
+  fullscreen_delegate.ResetState();
+
+  // Simulate another enter. As the tab is already fullscreen the delegate
+  // should not be notified again.
+  static_cast<content::WebContentsDelegate*>(tab)->EnterFullscreenModeForTab(
+      nullptr, blink::mojom::FullscreenOptions());
+  EXPECT_TRUE(static_cast<content::WebContentsDelegate*>(tab)
+                  ->IsFullscreenForTabOrPending(nullptr));
+  EXPECT_FALSE(fullscreen_delegate.got_enter());
+  EXPECT_FALSE(fullscreen_delegate.got_exit());
+
+  tab->SetFullscreenDelegate(nullptr);
+}
+
 }  // namespace weblayer

weblayer/browser/tab_impl.cc

@@ -1092,6 +1092,12 @@ void TabImpl::EnterFullscreenModeForTab(
     content::RenderFrameHost* requesting_frame,
     const blink::mojom::FullscreenOptions& options) {
   // TODO: support |options|.
+  if (is_fullscreen_) {
+    // Typically EnterFullscreenModeForTab() should not be called consecutively,
+    // but there may be corner cases with oopif that lead to multiple
+    // consecutive calls. Avoid notifying the delegate in this case.
+    return;
+  }
   is_fullscreen_ = true;
   if (!IsActive()) {
     // Process the request the tab is made active.