Should handle the events when no printer is detected on local

machineGetDefaultPrintSettings was returning an empty struct because no printer
is installed. Checking when its empty will allow us to know that a printer is
missing on that system. There is clearly no other way to do this, unless we do
not do all those dchecks on dpi and other struct members.BUG=6835TEST=Tested
only on windows, since linux/mac printing not even implemented. Removed all
printer drivers, opened chromium, and ran a print job, popup dialog appeared
stating no printer installed. Installed my printer drivers again, print dialog
appeared.

Patch contributed by Mohamed Mansour <m0.interactive@gmail.com>

Review: http://codereview.chromium.org/100023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@14731 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 19 insertions, 1 deletions

diff --git a/chrome/app/generated_resources.grd b/chrome/app/generated_resources.grd
index ad9f703..27ca552 100644
--- a/chrome/app/generated_resources.grd
+++ b/chrome/app/generated_resources.grd
@@ -2363,10 +2363,13 @@ each locale. -->
         Update server not available (error: <ph name="ERROR_NUMBER">$1<ex>1</ex></ph>)
       </message>
 
-      <!-- Print preview UI -->
+      <!-- Print -->
       <message name="IDS_DEFAULT_PRINT_DOCUMENT_TITLE" desc="Default title for a print document">
         Untitled Document
       </message>
+      <message name="IDS_DEFAULT_PRINTER_NOT_FOUND_WARNING_TITLE" desc="Title of the warning dialog when no when no printer is available">
+        No printer found, Please install a printer.
+      </message>
 
       <!-- Tabs -->
       <message name="IDS_TAB_LOADING_TITLE" desc="The text to be displayed in the title of a tab before a title is discovered.">
diff --git a/chrome/common/render_messages.h b/chrome/common/render_messages.h
index e0c6004..c689365 100644
--- a/chrome/common/render_messages.h
+++ b/chrome/common/render_messages.h
@@ -309,6 +309,12 @@ struct ViewMsg_Print_Params {
            max_shrink == rhs.max_shrink &&
            desired_dpi == rhs.desired_dpi;
   }
+
+  // Checking if the current params is empty. Just initialized after a memset.
+  bool IsEmpty() const {
+    return !document_cookie && !desired_dpi && !max_shrink && !min_shrink &&
+           !dpi && printable_size.IsEmpty();
+  }
 };
 
 struct ViewMsg_PrintPage_Params {
diff --git a/chrome/renderer/render_view.cc b/chrome/renderer/render_view.cc
index 0f5b80e..bce6d4c 100644
--- a/chrome/renderer/render_view.cc
+++ b/chrome/renderer/render_view.cc
@@ -2340,6 +2340,15 @@ void RenderView::ScriptedPrint(WebFrame* frame) {
       new ViewHostMsg_GetDefaultPrintSettings(routing_id_, &default_settings);
   if (Send(msg)) {
     msg = NULL;
+    // Check if the printer returned any settings, if the settings is empty, we
+    // can safely assume there are no printer drivers configured. So we safely
+    // terminate.
+    if (default_settings.IsEmpty()) {
+      RunJavaScriptAlert(frame,
+          l10n_util::GetString(IDS_DEFAULT_PRINTER_NOT_FOUND_WARNING_TITLE));
+      return;
+    }
+
     // Continue only if the settings are valid.
     if (default_settings.dpi && default_settings.document_cookie) {
       int expected_pages_count = 0;