Rewrite std::string("") to std::string(), Linux edition.

This patch was generated by running the empty_string clang tool
across the Chromium Linux compilation database. Implicitly or
explicitly constructing std::string() with a "" argument is
inefficient as the caller needs to emit extra instructions to
pass an argument, and the constructor needlessly copies a byte
into internal storage. Rewriting these instances to simply call
the default constructor appears to save ~14-18 kilobytes on an
optimized release build.

BUG=none

Review URL: https://codereview.chromium.org/13145003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@193020 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 12 insertions, 15 deletions

diff --git a/chrome/browser/extensions/api/extension_action/browser_action_apitest.cc b/chrome/browser/extensions/api/extension_action/browser_action_apitest.cc
index 0a5497f..07845e4 100644
--- a/chrome/browser/extensions/api/extension_action/browser_action_apitest.cc
+++ b/chrome/browser/extensions/api/extension_action/browser_action_apitest.cc
@@ -692,11 +692,9 @@ IN_PROC_BROWSER_TEST_F(BrowserActionApiTest, TestTriggerBrowserAction) {
       "window.domAutomationController.send(document.body.style."
       "backgroundColor);";
   std::string result;
-  const std::string frame_xpath = "";
-  EXPECT_TRUE(content::ExecuteScriptInFrameAndExtractString(tab,
-                                                            frame_xpath,
-                                                            script,
-                                                            &result));
+  const std::string frame_xpath;
+  EXPECT_TRUE(content::ExecuteScriptInFrameAndExtractString(
+      tab, frame_xpath, script, &result));
   EXPECT_EQ(result, "red");
 }
 
diff --git a/chrome/browser/extensions/api/extension_action/page_action_apitest.cc b/chrome/browser/extensions/api/extension_action/page_action_apitest.cc
index 232280a..cad5250 100644
--- a/chrome/browser/extensions/api/extension_action/page_action_apitest.cc
+++ b/chrome/browser/extensions/api/extension_action/page_action_apitest.cc
@@ -63,7 +63,7 @@ IN_PROC_BROWSER_TEST_F(PageActionApiTest, Basic) {
     ExtensionService* service = extensions::ExtensionSystem::Get(
         browser()->profile())->extension_service();
     service->browser_event_router()->PageActionExecuted(
-        browser()->profile(), *action, tab_id, "", 0);
+        browser()->profile(), *action, tab_id, std::string(), 0);
     EXPECT_TRUE(catcher.GetNextResult());
   }
 
@@ -108,7 +108,7 @@ IN_PROC_BROWSER_TEST_F(PageActionApiTest, AddPopup) {
     ExtensionService* service = extensions::ExtensionSystem::Get(
         browser()->profile())->extension_service();
     service->browser_event_router()->PageActionExecuted(
-        browser()->profile(), *page_action, tab_id, "", 1);
+        browser()->profile(), *page_action, tab_id, std::string(), 1);
     ASSERT_TRUE(catcher.GetNextResult());
   }
 
@@ -188,7 +188,7 @@ IN_PROC_BROWSER_TEST_F(PageActionApiTest, OldPageActions) {
         browser()->profile())->extension_service();
     ExtensionAction* page_action = GetPageAction(*extension);
     service->browser_event_router()->PageActionExecuted(
-        browser()->profile(), *page_action, tab_id, "", 1);
+        browser()->profile(), *page_action, tab_id, std::string(), 1);
     EXPECT_TRUE(catcher.GetNextResult());
   }
 }
@@ -260,7 +260,7 @@ IN_PROC_BROWSER_TEST_F(PageActionApiTest, TestTriggerPageAction) {
     ExtensionService* service = extensions::ExtensionSystem::Get(
         browser()->profile())->extension_service();
     service->browser_event_router()->PageActionExecuted(
-        browser()->profile(), *page_action, tab_id, "", 0);
+        browser()->profile(), *page_action, tab_id, std::string(), 0);
     EXPECT_TRUE(catcher.GetNextResult());
   }
 
@@ -273,11 +273,9 @@ IN_PROC_BROWSER_TEST_F(PageActionApiTest, TestTriggerPageAction) {
       "window.domAutomationController.send(document.body.style."
       "backgroundColor);";
   std::string result;
-  const std::string frame_xpath = "";
-  EXPECT_TRUE(content::ExecuteScriptInFrameAndExtractString(tab,
-                                                            frame_xpath,
-                                                            script,
-                                                            &result));
+  const std::string frame_xpath;
+  EXPECT_TRUE(content::ExecuteScriptInFrameAndExtractString(
+      tab, frame_xpath, script, &result));
   EXPECT_EQ(result, "red");
 }
 
diff --git a/chrome/browser/extensions/api/extension_action/script_badge_apitest.cc b/chrome/browser/extensions/api/extension_action/script_badge_apitest.cc
index fd32e96..ff7fae7 100644
--- a/chrome/browser/extensions/api/extension_action/script_badge_apitest.cc
+++ b/chrome/browser/extensions/api/extension_action/script_badge_apitest.cc
@@ -88,7 +88,8 @@ IN_PROC_BROWSER_TEST_F(ScriptBadgeApiTest, Basics) {
     ResultCatcher catcher;
     // Visit a non-extension page so the extension can run a content script and
     // cause the script badge to be animated in.
-    ui_test_utils::NavigateToURL(browser(), test_server()->GetURL(""));
+    ui_test_utils::NavigateToURL(browser(),
+                                 test_server()->GetURL(std::string()));
     ASSERT_TRUE(catcher.GetNextResult());
   }
   EXPECT_TRUE(script_badge->GetIsVisible(tab_id));