Created min size for print preview dialog and modified to allow the

chrome/browser/printing/print_preview_dialog_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/printing/print_preview_dialog_controller.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <string>
@@ skipping 60 matching lines @@
 };
 
 PrintPreviewDialogDelegate::PrintPreviewDialogDelegate(WebContents* initiator)
     : initiator_(initiator) {
 }
 
 PrintPreviewDialogDelegate::~PrintPreviewDialogDelegate() {
 }
 
 ui::ModalType PrintPreviewDialogDelegate::GetDialogModalType() const {
-  // Not used, returning dummy value.
-  NOTREACHED();
-  return ui::MODAL_TYPE_WINDOW;
+  return ui::MODAL_TYPE_CHILD;
 }
 
 base::string16 PrintPreviewDialogDelegate::GetDialogTitle() const {
   // Only used on Windows? UI folks prefer no title.
   return base::string16();
 }
 
 GURL PrintPreviewDialogDelegate::GetDialogContentURL() const {
   return GURL(chrome::kChromeUIPrintURL);
 }
 
 void PrintPreviewDialogDelegate::GetWebUIMessageHandlers(
     std::vector<WebUIMessageHandler*>* /* handlers */) const {
   // PrintPreviewUI adds its own message handlers.
 }
 
 void PrintPreviewDialogDelegate::GetDialogSize(gfx::Size* size) const {
   DCHECK(size);
+  const int kBorder = 25;
+// Gives ChromeOS dialogs the requested minimum size of 438x455 without changing
+// the existing behavior on Mac OSX. For all other platforms, the min size
+// is later overriden by the size of the parent window.

[Lei Zhang, 2016/08/18 20:30:57]

overridden?

[rbpotter, 2016/08/19 01:59:09]

Done.

+#if defined(OS_MACOSX)
   const gfx::Size kMinDialogSize(800, 480);
-  const int kBorder = 25;
+#else
+  const gfx::Size kMinDialogSize(438, 455);

[Lei Zhang, 2016/08/18 20:30:57]

So no behavior changes on Windows/Linux, right?

[rbpotter, 2016/08/19 01:59:09]

There will be no behavior changes in terms of the minimum size - it will still
shrink to the size of the parent window. The only thing that might change is
that it will keep its border within the parent window a little longer - once the
parent window gets small enough that the minimum size gets ignored the dialog
goes almost to the edge of the parent window since it no longer has its border.
Is this a problem?

[Lei Zhang, 2016/08/19 03:28:46]

No, seems ok.

+#endif
   *size = kMinDialogSize;
-
   web_modal::WebContentsModalDialogHost* host = nullptr;
   content::WebContents* outermost_web_contents =
       guest_view::GuestViewBase::GetTopLevelWebContents(initiator_);
   Browser* browser = chrome::FindBrowserWithWebContents(outermost_web_contents);
   if (browser)
     host = browser->window()->GetWebContentsModalDialogHost();
 
   if (host)
     size->SetToMax(host->GetMaximumDialogSize());
   else
     size->SetToMax(outermost_web_contents->GetContainerBounds().size());
+#if defined(OS_MACOSX)
   size->Enlarge(-2 * kBorder, -kBorder);
-
+#else
+  int expand_width =
+      std::min(size->width() - kMinDialogSize.width(), 2 * kBorder);
+  int expand_height =
+      std::min(size->height() - kMinDialogSize.height(), kBorder);
+  size->Enlarge(-expand_width, -expand_height);

[Lei Zhang, 2016/08/18 20:30:57]

Why not just calculate |expand_width| so it's negative in the first place? And
rename to shrink_width?

[rbpotter, 2016/08/19 01:59:09]

Done. I thought it was more readable to take the minimum of the desired  border
and the remaining size rather than doing a max of two negative values, and
renaming to "shrink" while making them negative would seem like we are shrinking
by a negative amount, when really we are expanding by a negative amount.

[Lei Zhang, 2016/08/19 03:28:46]

*shrug* If you like it better the other way, feel free to go back.

+#endif
 #if defined(OS_MACOSX)
   // Limit the maximum size on MacOS X.
   // http://crbug.com/105815
   const gfx::Size kMaxDialogSize(1000, 660);
   size->SetToMin(kMaxDialogSize);
 #endif
 }
 
 std::string PrintPreviewDialogDelegate::GetDialogArgs() const {
   return std::string();
@@ skipping 229 matching lines @@
 
   RemoveInitiator(contents);
 }
 
 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);
-
+      ShowNonClippedConstrainedWebDialog(
+          initiator->GetBrowserContext(),
+          new PrintPreviewDialogDelegate(initiator), initiator);
   WebContents* preview_dialog = web_dialog_delegate->GetWebContents();
 
   // 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
   // extension when iframed by the print preview dialog.
   GURL print_url(chrome::kChromeUIPrintURL);
   content::HostZoomMap::Get(preview_dialog->GetSiteInstance())
       ->SetZoomLevelForHostAndScheme(print_url.scheme(), print_url.host(), 0);
   PrintViewManager::CreateForWebContents(preview_dialog);
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
@@ skipping 85 matching lines @@
   if (initiator) {
     RemoveObservers(initiator);
     PrintViewManager::FromWebContents(initiator)->PrintPreviewDone();
   }
 
   preview_dialog_map_.erase(preview_dialog);
   RemoveObservers(preview_dialog);
 }
 
 }  // namespace printing