[subresource_filter] Use constexpr for subresource filter dev tools messages.

chrome/browser/subresource_filter/subresource_filter_browsertest.cc

Index: chrome/browser/subresource_filter/subresource_filter_browsertest.cc
diff --git a/chrome/browser/subresource_filter/subresource_filter_browsertest.cc b/chrome/browser/subresource_filter/subresource_filter_browsertest.cc
index 8eb565c528895a579ba0c73b57c58e9718e15933..ab478859444917b94d27b03c3d7aef3f1d70dc28 100644
--- a/chrome/browser/subresource_filter/subresource_filter_browsertest.cc
+++ b/chrome/browser/subresource_filter/subresource_filter_browsertest.cc
@@ -4,6 +4,7 @@
 
 #include <map>
 #include <memory>
+#include <sstream>
 #include <string>
 
 #include "base/bind.h"
@@ -544,8 +545,10 @@ IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
 }
 
 IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest, SubFrameActivation) {
-  content::ConsoleObserverDelegate console_observer(
-      web_contents(), kDisallowSubframeConsoleMessage + "*");
+  std::ostringstream message_filter;
+  message_filter << kDisallowSubframeConsoleMessage << "*";
+  content::ConsoleObserverDelegate console_observer(web_contents(),
+                                                    message_filter.str());
   web_contents()->SetDelegate(&console_observer);
 
   GURL url(GetTestUrl(kTestFrameSetPath));
@@ -564,15 +567,17 @@ IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest, SubFrameActivation) {
                            1);
 
   // Console message for subframe blocking should be displayed.
-  EXPECT_TRUE(base::MatchPattern(
-      console_observer.message(),
-      kDisallowSubframeConsoleMessage + "*included_script.js*"));
+  std::ostringstream result;
+  result << kDisallowSubframeConsoleMessage << "*included_script.js*";
+  EXPECT_TRUE(base::MatchPattern(console_observer.message(), result.str()));
 }
 
 IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
                        ActivationDisabled_NoConsoleMessage) {
-  content::ConsoleObserverDelegate console_observer(
-      web_contents(), kDisallowSubframeConsoleMessage + "*");
+  std::ostringstream message_filter;
+  message_filter << kDisallowSubframeConsoleMessage << "*";
+  content::ConsoleObserverDelegate console_observer(web_contents(),
+                                                    message_filter.str());
   web_contents()->SetDelegate(&console_observer);
 
   Configuration config(
@@ -594,8 +599,10 @@ IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(SubresourceFilterBrowserTest,
                        ActivationDryRun_NoConsoleMessage) {
-  content::ConsoleObserverDelegate console_observer(
-      web_contents(), kDisallowSubframeConsoleMessage + "*");
+  std::ostringstream message_filter;
+  message_filter << kDisallowSubframeConsoleMessage << "*";
+  content::ConsoleObserverDelegate console_observer(web_contents(),
+                                                    message_filter.str());
   web_contents()->SetDelegate(&console_observer);
 
   Configuration config(