[session restore] Prevent restored windows from being completely white.

Since https://crrev.com/701411, restoring a window that was "last active"
and "minimized" when it was closed opens a window that is completely
white. This is because the window is activated but never shown.

This CL ensures that the window that gets activated when restoring a
session is also shown.

Bug: 1018885
Change-Id: I9d01bfb2cafa83df9744bf5c598570ff55252de0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1884952Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710397}

chrome/browser/sessions/session_restore.cc

@@ -470,8 +470,12 @@ class SessionRestoreImpl : public BrowserListObserver {
     chromeos::BootTimesRecorder::Get()->AddLoginTimeMarker(
         "SessionRestore-CreatingTabs-End", false);
 #endif
-    if (browser_to_activate)
+    if (browser_to_activate) {
+      // |browser_to_activate| may be minimized. Show it before activating it to
+      // avoid having a window with no content. https://crbug.com/1018885
+      browser_to_activate->window()->Show();
       browser_to_activate->window()->Activate();
+    }
 
     // If last_browser is NULL and urls_to_open_ is non-empty,
     // FinishedTabCreation will create a new TabbedBrowser and add the urls to

chrome/browser/sessions/session_restore_browsertest.cc

@@ -368,6 +368,23 @@ IN_PROC_BROWSER_TEST_F(SessionRestoreTest, RestoredTabsShouldHaveWindow) {
   }
 }
 
+// Verify that restoring a minimized window does not create a blank window.
+// Regression test for https://crbug.com/1018885.
+IN_PROC_BROWSER_TEST_F(SessionRestoreTest, RestoreMinimizedWindow) {
+  // Minimize the window.
+  browser()->window()->Minimize();
+
+  // Restart and session restore the tabs.
+  Browser* restored = QuitBrowserAndRestore(browser(), 3);
+  EXPECT_EQ(1, restored->tab_strip_model()->count());
+
+  // Expect the window to be visible.
+  // Prior to the fix for https://crbug.com/1018885, the window was active but
+  // not visible.
+  EXPECT_TRUE(restored->window()->IsActive());
+  EXPECT_TRUE(restored->window()->IsVisible());
+}
+
 // Verify that restored tabs have correct disposition. Only one tab should
 // have "visible" visibility state, the rest should not.
 // (http://crbug.com/155365 http://crbug.com/118269)