Combine tab background image getter code into one place.

chrome/browser/ui/views/tabs/tab_strip.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/ui/views/tabs/tab_strip.h"
 
 #include <algorithm>
 #include <iterator>
 #include <string>
 #include <vector>
@@ skipping 380 matching lines @@
     mask->close();
   }
 
   return true;
 }
 
 void NewTabButton::PaintFill(bool pressed,
                              double hover_value,
                              float scale,
                              gfx::Canvas* canvas) const {
-  int bg_id = IDR_THEME_TAB_BACKGROUND_V;
-  if (!GetWidget()->ShouldWindowContentsBeTransparent()) {
-    bg_id = tab_strip_->controller()->IsIncognito() ?
-        IDR_THEME_TAB_BACKGROUND_INCOGNITO : IDR_THEME_TAB_BACKGROUND;
-  }
+  bool custom_image;
+  const int bg_id = tab_strip_->GetBackgroundResourceId(&custom_image);
 
   // Draw the fill background image.
   const gfx::Size size(GetNewTabButtonSize());
   ui::ThemeProvider* theme_provider = GetThemeProvider();
   gfx::ImageSkia* background = theme_provider->GetImageSkiaNamed(bg_id);
   // For custom tab backgrounds the background starts at the top of the tab
   // strip. Otherwise the background starts at the top of the frame.
   const int offset_y = theme_provider->HasCustomImage(bg_id) ?
       0 : background_offset_.y();
 
@@ skipping 785 matching lines @@
       clip->SetRect(x, 0, tab_bounds.width() - x, tab_bounds.height());
     }
   }
   return true;
 }
 
 bool TabStrip::IsImmersiveStyle() const {
   return immersive_style_;
 }
 
+int TabStrip::GetBackgroundResourceId(bool* custom_image) const {
+  ui::ThemeProvider* theme_provider = GetThemeProvider();
+
+  if (GetWidget()->ShouldWindowContentsBeTransparent()) {
+    const int kBackgroundIdGlass = IDR_THEME_TAB_BACKGROUND_V;
+    *custom_image = theme_provider->HasCustomImage(kBackgroundIdGlass);
+    return kBackgroundIdGlass;
+  }
+
+  // If a custom theme does not provide a replacement tab background, but does
+  // provide a replacement frame image, HasCustomImage() on the tab background
+  // ID will return false, but the theme provider will make a custom image from
+  // the frame image.
+  const bool incognito = controller()->IsIncognito();
+  const int id = incognito ?
+      IDR_THEME_TAB_BACKGROUND_INCOGNITO : IDR_THEME_TAB_BACKGROUND;
+  *custom_image = theme_provider->HasCustomImage(id) ||
+      theme_provider->HasCustomImage(
+          incognito ? IDR_THEME_FRAME_INCOGNITO : IDR_THEME_FRAME);
+  return id;
+}
+
 void TabStrip::UpdateTabAccessibilityState(const Tab* tab,
                                            ui::AXViewState* state) {
   state->count = tab_count();
   state->index = GetModelIndexOfTab(tab);
 }
 
 void TabStrip::MouseMovedOutOfHost() {
   ResizeLayoutTabs();
   if (reset_to_shrink_on_exit_) {
     reset_to_shrink_on_exit_ = false;
@@ skipping 1441 matching lines @@
           ConvertPointToViewAndGetEventHandler(this, newtab_button_, point);
       if (view)
         return view;
     }
     Tab* tab = FindTabForEvent(point);
     if (tab)
       return ConvertPointToViewAndGetEventHandler(this, tab, point);
   }
   return this;
 }