Adding a way to associate Android Activities with PlatformWindowAndroid

ui/platform_window/android/platform_window_android.cc

Index: ui/platform_window/android/platform_window_android.cc
diff --git a/ui/platform_window/android/platform_window_android.cc b/ui/platform_window/android/platform_window_android.cc
index 49b6ba7b3357786af2331befc6823c7d3abf1cfd..3ab190542904f9584fb7d3460de1eb534fd3035b 100644
--- a/ui/platform_window/android/platform_window_android.cc
+++ b/ui/platform_window/android/platform_window_android.cc
@@ -72,6 +72,11 @@ void PlatformWindowAndroid::Destroy(JNIEnv* env, jobject obj) {
   delegate_->OnClosed();
 }
 
+void PlatformWindowAndroid::JavaPlatformWindowCreated(
+    JNIEnv* env, jobject obj) {
+  java_platform_window_android_ = JavaObjectWeakGlobalRef(env, obj);
+}
+
 void PlatformWindowAndroid::SurfaceCreated(JNIEnv* env,
                                            jobject obj,
                                            jobject jsurface,
@@ -152,14 +157,7 @@ void PlatformWindowAndroid::ReleaseWindow() {
 // PlatformWindowAndroid, PlatformWindow implementation:
 
 void PlatformWindowAndroid::Show() {
-  if (!java_platform_window_android_.is_empty())
-    return;
-  JNIEnv* env = base::android::AttachCurrentThread();
-  java_platform_window_android_ = JavaObjectWeakGlobalRef(
-      env, Java_PlatformWindowAndroid_createForActivity(
-               env, base::android::GetApplicationContext(),
-               reinterpret_cast<jlong>(this),
-               reinterpret_cast<jlong>(&platform_ime_controller_)).obj());
+  CHECK(!java_platform_window_android_.is_empty());
 }
 
 void PlatformWindowAndroid::Hide() {