Move nsimage_cache into base so that it can be accessed from outside of chrome

chrome/browser/cocoa/nsimage_cache_unittest.mm

 // Copyright (c) 2009 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/file_path.h"
 #include "base/mac_util.h"
+#include "base/nsimage_cache_mac.h"
 #include "base/path_service.h"
-#include "chrome/browser/cocoa/nsimage_cache.h"
 #include "chrome/common/mac_app_names.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "testing/platform_test.h"
 
+// This tests nsimage_cache, which lives in base/.  The unit test is in
+// chrome/ because it depends on having a built-up Chrome present.
+
 namespace {
 
 class NSImageCacheTest : public PlatformTest {
  public:
   NSImageCacheTest() {
     // Look in the Chromium app bundle for resources.
     FilePath path;
     PathService::Get(base::DIR_EXE, &path);
     path = path.AppendASCII(MAC_BROWSER_APP_NAME);
     mac_util::SetOverrideAppBundlePath(path);
@@ skipping 22 matching lines @@
 TEST_F(NSImageCacheTest, LookupFoundAndClear) {
   NSImage *first = nsimage_cache::ImageNamed(@"back_Template.pdf");
   EXPECT_TRUE(first != nil)
       << "Failed to find the toolbar image?";
   nsimage_cache::Clear();
   EXPECT_NE(first, nsimage_cache::ImageNamed(@"back_Template.pdf"))
       << "how'd we get the same image after a cache clear?";
 }
 
 }  // namespace