Rename the various shell MojoMains to ShellMain.

shell/android/library_loader.cc

Index: shell/android/library_loader.cc
diff --git a/shell/android/library_loader.cc b/shell/android/library_loader.cc
index c6d31de64770e300260c1accc7eb9432af00149d..d5230ac36ab8e7e23489adfa321805c59bd761b7 100644
--- a/shell/android/library_loader.cc
+++ b/shell/android/library_loader.cc
@@ -17,9 +17,9 @@ namespace {
 base::android::RegistrationMethod kMojoRegisteredMethods[] = {
     {"AndroidHandler", mojo::shell::RegisterAndroidHandlerJni},
     {"Keyboard", mojo::shell::RegisterKeyboardJni},
-    {"MojoMain", mojo::shell::RegisterMojoMain},
     {"PlatformViewportAndroid",
      native_viewport::PlatformViewportAndroid::Register},
+    {"ShellMain", mojo::shell::RegisterShellMain},
 };
 
 bool RegisterJNI(JNIEnv* env) {