Fix the warnings when build content/ with clang

content/shell/shell_android.cc

Index: content/shell/shell_android.cc
diff --git a/content/shell/shell_android.cc b/content/shell/shell_android.cc
index 859184ba946c593e23d8e66ec8fe7feaee4f3311..393d9a12b0b6c01dbef641294baf6cacf9297d06 100644
--- a/content/shell/shell_android.cc
+++ b/content/shell/shell_android.cc
@@ -60,7 +60,7 @@ void Shell::PlatformSetTitle(const string16& title) {
   NOTIMPLEMENTED();
 }
 
-void Shell::LoadProgressChanged(double progress) {
+void Shell::LoadProgressChanged(WebContents* source, double progress) {
   JNIEnv* env = AttachCurrentThread();
   Java_Shell_onLoadProgressChanged(env, java_object_.obj(), progress);
 }