Do not cache the tab background if a tab background was autogenerated by a theme

chrome/browser/ui/views/tabs/tab.cc

Index: chrome/browser/ui/views/tabs/tab.cc
diff --git a/chrome/browser/ui/views/tabs/tab.cc b/chrome/browser/ui/views/tabs/tab.cc
index 0389cc1f34affcb61a24a649411cfcb745af2910..99694ff5d8e18f33040352c679ad5fa09654d208 100644
--- a/chrome/browser/ui/views/tabs/tab.cc
+++ b/chrome/browser/ui/views/tabs/tab.cc
@@ -1154,23 +1154,33 @@ void Tab::PaintInactiveTabBackgroundWithTitleChange(
 
 void Tab::PaintInactiveTabBackground(gfx::Canvas* canvas) {
   int tab_id;
+  int tab_base_id;
   views::Widget* widget = GetWidget();
   if (widget && widget->GetTopLevelWidget()->ShouldUseNativeFrame()) {
     tab_id = IDR_THEME_TAB_BACKGROUND_V;
+    tab_base_id = 0;

[sky, 2013/02/11 21:21:55]

Is 0 known to be ignored? I think I would rather have the if below not ask if
tab_base_id == 0. Also, wouldn't a better name for tab_base_id be frame_id?

   } else if (data().incognito) {
     tab_id = IDR_THEME_TAB_BACKGROUND_INCOGNITO;
+    tab_base_id = IDR_THEME_FRAME_INCOGNITO;
 #if defined(OS_WIN)
   } else if (win8::IsSingleWindowMetroMode()) {
     tab_id = IDR_THEME_TAB_BACKGROUND_V;
+    tab_base_id = 0;
 #endif
   } else {
     tab_id = IDR_THEME_TAB_BACKGROUND;
+    tab_base_id = IDR_THEME_FRAME;
   }
   // Explicitly map the id so we cache correctly.
   const chrome::HostDesktopType host_desktop_type = GetHostDesktopType(this);
   tab_id = chrome::MapThemeImage(host_desktop_type, tab_id);
 
-  const bool can_cache = !GetThemeProvider()->HasCustomImage(tab_id) &&
+  // Do not cache the tab background if the theme provides a custom tab
+  // background or if a tab background was autogenerated by the theme
+  // machinery.
+  ui::ThemeProvider* theme_provider = GetThemeProvider();
+  const bool can_cache = !theme_provider->HasCustomImage(tab_id) &&
+      !theme_provider->HasCustomImage(tab_base_id) &&
       !hover_controller_.ShouldDraw();
 
   if (can_cache) {