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..8a05d239857929758b411d4ea7b0f1d681d7cd12 100644
--- a/ui/platform_window/android/platform_window_android.cc
+++ b/ui/platform_window/android/platform_window_android.cc
@@ -51,6 +51,12 @@ bool PlatformWindowAndroid::Register(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
+//static
+PlatformWindowAndroid* PlatformWindowAndroid::From(
+    PlatformWindow* platform_window) {
+  return static_cast<PlatformWindowAndroid*>(platform_window);
+}
+
 PlatformWindowAndroid::PlatformWindowAndroid(PlatformWindowDelegate* delegate)
     : delegate_(delegate),
       window_(NULL),
@@ -68,6 +74,21 @@ PlatformWindowAndroid::~PlatformWindowAndroid() {
   }
 }
 
+void PlatformWindowAndroid::AttachToActivity(jobject activity) {
+  JNIEnv* env = base::android::AttachCurrentThread();

[sadrul, 2015/12/01 21:29:34]

Should this DCHECK(!IsAttachedToActivity())? Or is it possible to change the
activity this is attached to?

[mfomitchev, 2015/12/01 21:50:50]

I'll add the DCHECK for now. If we need to change the attached activity, we can
always change this later.

+  base::android::ScopedJavaLocalRef<jobject> jpwa =
+      Java_PlatformWindowAndroid_createForActivity(
+          env,
+          activity,
+          reinterpret_cast<jlong>(this),
+          reinterpret_cast<jlong>(&platform_ime_controller_));
+  java_platform_window_android_ = JavaObjectWeakGlobalRef(env, jpwa.obj());
+}
+
+bool PlatformWindowAndroid::IsAttachedToActivity() {
+  return !java_platform_window_android_.is_empty();
+}
+
 void PlatformWindowAndroid::Destroy(JNIEnv* env, jobject obj) {
   delegate_->OnClosed();
 }
@@ -152,14 +173,7 @@ 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());
+  DCHECK(IsAttachedToActivity());
 }

[sadrul, 2015/12/01 21:29:34]

Should this set visibility on the android SurfaceView?

[mfomitchev, 2015/12/01 21:50:51]

Considering we are not doing anything in Hide(), I don't think we need to be
doing anything here? I expect that the SurfaceView state will be updated on the
Android site through standard Android mechanisms when the window is minimized,
obscured, etc. We might want to hook up Android visibility state to native
Show/Hide, but I think that would be a separate CL. This CL just keeps things
the way they were in that regard.

 
 void PlatformWindowAndroid::Hide() {