Try two different pixel results for mac for the PDFBrowserTest.Basic test.

chrome/browser/ui/pdf/pdf_browsertest.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 "base/file_util.h"
 #include "base/path_service.h"
 #include "base/string_number_conversions.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 62 matching lines @@
     ASSERT_GT(screen_bounds.width(), kBrowserWidth);
     ASSERT_GT(screen_bounds.height(), kBrowserHeight);
     browser()->window()->SetBounds(bounds);
 
     GURL url(ui_test_utils::GetTestUrl(
         GetPDFTestDir(),
         FilePath(FILE_PATH_LITERAL("pdf_browsertest.pdf"))));
     ui_test_utils::NavigateToURL(browser(), url);
   }
 
-  void VerifySnapshot(const std::string& expected_filename) {
+  bool VerifySnapshot(const std::string& expected_filename) {
     snapshot_different_ = true;
     expected_filename_ = expected_filename;
     TabContents* tab_contents =  chrome::GetActiveTabContents(browser());
     tab_contents->snapshot_tab_helper()->CaptureSnapshot();
     ui_test_utils::RegisterAndWait(
         this,
         chrome::NOTIFICATION_TAB_SNAPSHOT_TAKEN,
         content::Source<WebContents>(tab_contents->web_contents()));
-    ASSERT_FALSE(snapshot_different_) << "Rendering didn't match, see result "
-        "at " << snapshot_filename_.value().c_str();
+    if (snapshot_different_) {
+      LOG(INFO) << "Rendering didn't match, see result " <<
+          snapshot_filename_.value().c_str();
+    }
+    return !snapshot_different_;
   }
 
   void WaitForResponse() {
     // Even if the plugin has loaded the data or scrolled, because of how
     // pepper painting works, we might not have the data.  One way to force this
     // to be flushed is to do a find operation, since on this two-page test
     // document, it'll wait for us to flush the renderer message loop twice and
     // also the browser's once, at which point we're guaranteed to have updated
     // the backingstore.  Hacky, but it works.
     // Note that we need to change the text each time, because if we don't the
@@ skipping 89 matching lines @@
   FilePath snapshot_filename_;
   // How many times we've seen chrome::LOAD_STOP.
   int load_stop_notification_count_;
 
   scoped_ptr<net::TestServer> pdf_test_server_;
 };
 
 #if defined(OS_CHROMEOS)
 // TODO(sanjeevr): http://crbug.com/79837
 #define MAYBE_Basic DISABLED_Basic
-#elif defined(OS_MACOSX)
-// Fails on release builder for Mac: http://crbug.com/142531
-#define MAYBE_Basic DISABLED_Basic
 #else
 #define MAYBE_Basic Basic
 #endif
 // Tests basic PDF rendering.  This can be broken depending on bad merges with
 // the vendor, so it's important that we have basic sanity checking.
 IN_PROC_BROWSER_TEST_F(PDFBrowserTest, MAYBE_Basic) {
   ASSERT_NO_FATAL_FAILURE(Load());
   ASSERT_NO_FATAL_FAILURE(WaitForResponse());
   // OS X uses CoreText, and FreeType renders slightly different on Linux and
   // Win.
 #if defined(OS_MACOSX)
-  std::string expectation_file = "pdf_browsertest_mac.png";
+  // The bots render differently than locally, see http://crbug.com/142531.
+  ASSERT_TRUE(VerifySnapshot("pdf_browsertest_mac.png") ||
+              VerifySnapshot("pdf_browsertest_mac2.png"));
 #elif defined(OS_LINUX)
-  std::string expectation_file = "pdf_browsertest_linux.png";
+  ASSERT_TRUE(VerifySnapshot("pdf_browsertest_linux.png"));
 #else
-  std::string expectation_file = "pdf_browsertest.png";
+  ASSERT_TRUE(VerifySnapshot("pdf_browsertest.png"));
 #endif
-  ASSERT_NO_FATAL_FAILURE(VerifySnapshot(expectation_file));
 }
 
 #if defined(OS_CHROMEOS)
 // TODO(sanjeevr): http://crbug.com/79837
 #define MAYBE_Scroll DISABLED_Scroll
 #else
 #define MAYBE_Scroll Scroll
 #endif
 // Tests that scrolling works.
 IN_PROC_BROWSER_TEST_F(PDFBrowserTest, MAYBE_Scroll) {
@@ skipping 123 matching lines @@
       chrome::GetActiveWebContents(browser())->GetRenderViewHost(),
       std::wstring(),
       L"reloadPDF();"));
   observer.Wait();
 
   ASSERT_EQ("success",
             chrome::GetActiveWebContents(browser())->GetURL().query());
 }
 
 }  // namespace