Theme suppliers: Avoid all Image copying.

chrome/browser/themes/theme_service.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/themes/theme_service.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 
@@ skipping 654 matching lines @@
     const double luminance = color_utils::GetRelativeLuminance(
         color_utils::AlphaBlend(separator_color, frame_color, alpha));
     if (luminance == target_luminance)
       break;
     alpha += (luminance < target_luminance) ? -delta : delta;
   }
   return SkColorSetA(separator_color, alpha);
 }
 
 gfx::ImageSkia* ThemeService::GetImageSkiaNamed(int id, bool incognito) const {
-  gfx::Image image = GetImageNamed(id, incognito);
+  const gfx::Image& image = GetImageNamed(id, incognito);
   if (image.IsEmpty())
     return nullptr;
   // TODO(pkotwicz): Remove this const cast.  The gfx::Image interface returns
   // its images const. GetImageSkiaNamed() also should but has many callsites.
   return const_cast<gfx::ImageSkia*>(image.ToImageSkia());
 }
 
 SkColor ThemeService::GetColor(int id, bool incognito) const {
   DCHECK(CalledOnValidThread());
 
@@ skipping 51 matching lines @@
 
   base::RefCountedMemory* data = nullptr;
   if (theme_supplier_)
     data = theme_supplier_->GetRawData(id, scale_factor);
   if (!data)
     data = rb_.LoadDataResourceBytesForScale(id, ui::SCALE_FACTOR_100P);
 
   return data;
 }
 
-gfx::Image ThemeService::GetImageNamed(int id, bool incognito) const {
+const gfx::Image& ThemeService::GetImageNamed(int id, bool incognito) const {
   DCHECK(CalledOnValidThread());
 
   int adjusted_id = id;
   if (incognito) {
     if (id == IDR_THEME_FRAME)
       adjusted_id = IDR_THEME_FRAME_INCOGNITO;
     else if (id == IDR_THEME_FRAME_INACTIVE)
       adjusted_id = IDR_THEME_FRAME_INCOGNITO_INACTIVE;
   }
 
-  gfx::Image image;
-  if (theme_supplier_)
-    image = theme_supplier_->GetImageNamed(adjusted_id);
+  if (theme_supplier_) {
+    const gfx::Image& image = theme_supplier_->GetImageNamed(adjusted_id);
+    if (!image.IsEmpty())
+      return image;
+  }
 
-  if (image.IsEmpty())
-    image = rb_.GetNativeImageNamed(adjusted_id);
-
-  return image;
+  return rb_.GetNativeImageNamed(adjusted_id);
 }
 
 void ThemeService::OnExtensionServiceReady() {
   if (!ready_) {
     // If the ThemeService is not ready yet, the custom theme data pack needs to
     // be recreated from the extension.
     MigrateTheme();
     set_ready();
 
     // Send notification in case anyone requested data and cached it when the
@@ skipping 83 matching lines @@
 
 #if defined(ENABLE_SUPERVISED_USERS)
 bool ThemeService::IsSupervisedUser() const {
   return profile_->IsSupervised();
 }
 
 void ThemeService::SetSupervisedUserTheme() {
   SetCustomDefaultTheme(new SupervisedUserTheme);
 }
 #endif