Implement window.print() on Android

chrome/browser/printing/print_job_worker.cc

Index: chrome/browser/printing/print_job_worker.cc
diff --git a/chrome/browser/printing/print_job_worker.cc b/chrome/browser/printing/print_job_worker.cc
index 3f277c594182f0c9904fb903c3e1e70b1436946d..a0c713bc9130cc2721b7f836abdfd2d5e457aab6 100644
--- a/chrome/browser/printing/print_job_worker.cc
+++ b/chrome/browser/printing/print_job_worker.cc
@@ -24,6 +24,10 @@
 #include "printing/printing_utils.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(OS_ANDROID)
+#include "chrome/browser/android/tab_android.h"
+#endif
+
 using content::BrowserThread;
 
 namespace printing {
@@ -120,7 +124,8 @@ void PrintJobWorker::GetSettings(
     bool ask_user_for_settings,
     int document_page_count,
     bool has_selection,
-    MarginType margin_type) {
+    MarginType margin_type,
+    bool is_scripted) {
   DCHECK(task_runner_->RunsTasksOnCurrentThread());
   DCHECK_EQ(page_number_, PageNumber::npos());
 
@@ -141,7 +146,8 @@ void PrintJobWorker::GetSettings(
                    base::Bind(&PrintJobWorker::GetSettingsWithUI,
                               base::Unretained(this),
                               document_page_count,
-                              has_selection)));
+                              has_selection,
+                              is_scripted)));
   } else {
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
@@ -193,11 +199,30 @@ void PrintJobWorker::GetSettingsDone(PrintingContext::Result result) {
 
 void PrintJobWorker::GetSettingsWithUI(
     int document_page_count,
-    bool has_selection) {
+    bool has_selection,
+    bool is_scripted) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
+
+#if defined(OS_ANDROID)
+  if (is_scripted) {
+    PrintingContextDelegate* printing_context_delegate =
+        static_cast<PrintingContextDelegate*>(printing_context_delegate_.get());
+    content::WebContents* web_contents =
+        printing_context_delegate->GetWebContents();
+    TabAndroid* tab = TabAndroid::FromWebContents(web_contents);
+    if (tab) {
+      // If the following method fails (print not supported by policy, print
+      // in progress...) or is not called, attempting to start a pending print
+      // does nothing and will notify that printing is finished.

[Bernhard Bauer, 2014/12/15 10:44:59]

I'm not particularly familiar with this code, but I don't really understand this
comment, or rather what the consequences of that are. Why is that comment here
and not somewhere else, like where the method is declared?

[dgn, 2014/12/15 13:16:24]

Initially, the comment was there to clarify what happens if tab is nullptr and
the method is not called. The normal code path, after using
tab->setPendingPrint, would be to call PrintingController#StartPendingPrint().
So, I wrote it when I was trying to answer the question "what happens if the
pending print is not set up properly? Will javascript be hanging forever?"

I rewrote the comment and added something about failure in
PrintingController#StartPendingPrint's doc

+      tab->SetPendingPrint();
+    }
+  }
+#endif
+
   printing_context_->AskUserForSettings(
       document_page_count,
       has_selection,
+      is_scripted,
       base::Bind(&PrintJobWorker::GetSettingsWithUIDone,
                  base::Unretained(this)));
 }