Update VMRuntime.isBootClassPathOnDisk()...

... for the new boot image location specification.
In particular, use only the first component and, if there is
no path, use path from the first boot class path component.

Test: aosp_taimen-userdebug boots
Test: adb root && \
      adb shell stop && \
      adb shell setprop dalvik.vm.boot-image \
          'boot.art:boot-framework.art' &&
      adb shell start  # Starts correctly.
Test: adb root && \
      adb shell stop && \
      adb shell setprop dalvik.vm.boot-image \
          'boot.art:/system/framework/boot-framework.art' &&
      adb shell start  # Starts correctly.
Bug: 119868597
Change-Id: Ifae2a005b7c6b8625d744eca2df763e3f6f5d0fb
diff --git a/runtime/native/dalvik_system_VMRuntime.cc b/runtime/native/dalvik_system_VMRuntime.cc
index bb05e60..a4dc042 100644
--- a/runtime/native/dalvik_system_VMRuntime.cc
+++ b/runtime/native/dalvik_system_VMRuntime.cc
@@ -679,11 +679,7 @@
     env->ThrowNew(iae.get(), message.c_str());
     return JNI_FALSE;
   }
-  std::string error_msg;
-  Runtime* runtime = Runtime::Current();
-  std::unique_ptr<ImageHeader> image_header(gc::space::ImageSpace::ReadImageHeader(
-      runtime->GetImageLocation().c_str(), isa, runtime->GetImageSpaceLoadingOrder(), &error_msg));
-  return image_header.get() != nullptr;
+  return gc::space::ImageSpace::IsBootClassPathOnDisk(isa);
 }
 
 static jstring VMRuntime_getCurrentInstructionSet(JNIEnv* env, jclass) {