Reland of place string::find(prefix) == 0 pattern with base::StartsWith().

content/browser/iframe_zoom_browsertest.cc

 // Copyright 2016 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 <vector>
 
+#include "base/strings/string_util.h"
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/frame_host/render_frame_host_impl.h"
 #include "content/browser/web_contents/web_contents_impl.h"
 #include "content/public/browser/host_zoom_map.h"
 #include "content/public/browser/navigation_entry.h"
 #include "content/public/common/page_zoom.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/content_browser_test.h"
 #include "content/public/test/content_browser_test_utils.h"
 #include "content/public/test/test_navigation_observer.h"
@@ skipping 97 matching lines @@
     const char kOnResizeCallbackSetup[] =
         "document.body.onresize = function(){"
         "  window.domAutomationController.setAutomationId(0);"
         "  window.domAutomationController.send('%s ' + window.innerWidth);"
         "};";
     EXPECT_TRUE(ExecuteScript(
         adapter, base::StringPrintf(kOnResizeCallbackSetup, label.c_str())));
   }
 
   void Check(const std::string& status_msg) {
-    if (status_msg.find(msg_label) != 0)
+    if (!base::StartsWith(status_msg, msg_label, base::CompareCase::SENSITIVE))
       return;
 
     double inner_width = std::stod(status_msg.substr(msg_label.length() + 1));
     zoomed_correctly = std::abs(expected_inner_width - inner_width) < tolerance;
   }
 
   FrameResizeObserver* toThis() {return this;}
 
   RenderFrameHost* frame_host;
   std::string msg_label;
@@ skipping 336 matching lines @@
   EXPECT_EQ(redirect_url, web_contents()->GetLastCommittedURL());
 
   EXPECT_NEAR(
       kZoomFactorForRedirectedHost,
       GetMainFrameZoomFactor(web_contents(), main_frame_window_border),
       0.001);
 }
 #endif
 
 }  // namespace content