Implement PrintBrowser functionality.

chrome/browser/printing/print_preview_dialog_controller.cc

Index: chrome/browser/printing/print_preview_dialog_controller.cc
diff --git a/chrome/browser/printing/print_preview_dialog_controller.cc b/chrome/browser/printing/print_preview_dialog_controller.cc
index 780928be53474d99790f012a18a42736c78587d5..1c19971cac4deb7d51c32fbaddc6ee2793a326f2 100644
--- a/chrome/browser/printing/print_preview_dialog_controller.cc
+++ b/chrome/browser/printing/print_preview_dialog_controller.cc
@@ -11,6 +11,7 @@
 #include <vector>
 
 #include "base/auto_reset.h"
+#include "base/command_line.h"
 #include "base/macros.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
@@ -21,12 +22,17 @@
 #include "chrome/browser/printing/print_view_manager.h"
 #include "chrome/browser/task_manager/web_contents_tags.h"
 #include "chrome/browser/ui/browser.h"
+#include "chrome/browser/ui/browser_commands.h"
 #include "chrome/browser/ui/browser_finder.h"
+#include "chrome/browser/ui/browser_list.h"
+#include "chrome/browser/ui/browser_navigator.h"
 #include "chrome/browser/ui/browser_window.h"
+#include "chrome/browser/ui/tab_contents/core_tab_helper.h"
 #include "chrome/browser/ui/webui/chrome_web_contents_handler.h"
 #include "chrome/browser/ui/webui/constrained_web_dialog_ui.h"
 #include "chrome/browser/ui/webui/print_preview/print_preview_ui.h"
 #include "chrome/common/chrome_paths.h"
+#include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
 #include "components/guest_view/browser/guest_view_base.h"
 #include "components/web_modal/web_contents_modal_dialog_host.h"
@@ -343,6 +349,14 @@ void PrintPreviewDialogController::OnNavEntryCommitted(
         return;
       }
     }
+#if BUILDFLAG(ENABLE_PRINT_BROWSER)
+    // If in PrintBrowser mode, navigation away from the print UI is fine
+    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+    bool print_browser_enabled =
+        command_line->HasSwitch(switches::kEnablePrintBrowser);
+    if (print_browser_enabled)
+      return;
+#endif
     NOTREACHED();
     return;
   }
@@ -366,13 +380,37 @@ WebContents* PrintPreviewDialogController::CreatePrintPreviewDialog(
     WebContents* initiator) {
   base::AutoReset<bool> auto_reset(&is_creating_print_preview_dialog_, true);
 
-  // The dialog delegates are deleted when the dialog is closed.
-  ConstrainedWebDialogDelegate* web_dialog_delegate =
-      ShowConstrainedWebDialog(initiator->GetBrowserContext(),
-                               new PrintPreviewDialogDelegate(initiator),
-                               initiator);
+  WebContents* preview_dialog;
 
-  WebContents* preview_dialog = web_dialog_delegate->GetWebContents();
+#if BUILDFLAG(ENABLE_PRINT_BROWSER)
+  base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
+  bool print_browser_enabled =
+      command_line->HasSwitch(switches::kEnablePrintBrowser);
+  if (!print_browser_enabled) {
+#endif
+    // The dialog delegates are deleted when the dialog is closed.
+    ConstrainedWebDialogDelegate* web_dialog_delegate =
+        ShowConstrainedWebDialog(initiator->GetBrowserContext(),
+                                 new PrintPreviewDialogDelegate(initiator),
+                                 initiator);
+
+    preview_dialog = web_dialog_delegate->GetWebContents();
+#if BUILDFLAG(ENABLE_PRINT_BROWSER)
+  } else {
+    // If in PrintBrowser mode, swap |initiator| with a newly-created
+    // |preview_dialog| and navigate |preview_dialog| to the print UI
+    Browser* browser =
+        chrome::FindBrowserWithWindow(initiator->GetTopLevelNativeWindow());
+    preview_dialog =
+        WebContents::Create(WebContents::CreateParams(browser->profile()));
+    CoreTabHelper::FromWebContents(initiator)->delegate()->SwapTabContents(

[rbpotter, 2016/12/16 20:05:28]

I think you need to ensure the initiator web contents are destroyed at an
appropriate point after calling this.

+        initiator, preview_dialog, false, false);
+    browser->OpenURL(content::OpenURLParams(
+        GURL(chrome::kChromeUIPrintURL), content::Referrer(),
+        WindowOpenDisposition::CURRENT_TAB, ui::PAGE_TRANSITION_AUTO_TOPLEVEL,
+        false));
+  }
+#endif
 
   // Clear the zoom level for the print preview dialog so it isn't affected by
   // the default zoom level. This also controls the zoom level of the OOP PDF