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..bfa341c2a728bad985137fc14dbbc349c364e208 100644
--- a/ui/platform_window/android/platform_window_android.cc
+++ b/ui/platform_window/android/platform_window_android.cc
@@ -51,6 +51,19 @@ bool PlatformWindowAndroid::Register(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
+// static
+void PlatformWindowAndroid::createForActivity(
+    JNIEnv* env,
+    jobject activity,
+    jlong nativePlatformWindowAndroid,
+    jlong nativeImeController) {
+  Java_PlatformWindowAndroid_createForActivity(
+      env,
+      activity,
+      nativePlatformWindowAndroid,
+      nativeImeController);
+}
+
 PlatformWindowAndroid::PlatformWindowAndroid(PlatformWindowDelegate* delegate)
     : delegate_(delegate),
       window_(NULL),
@@ -72,6 +85,11 @@ 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 +170,7 @@ 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() {