Adding a way to associate Android Activities with PlatformWindowAndroid

ui/aura/window_tree_host_platform.cc

Index: ui/aura/window_tree_host_platform.cc
diff --git a/ui/aura/window_tree_host_platform.cc b/ui/aura/window_tree_host_platform.cc
index 10c50132dadf2e9a3013e0b29da5dfae52d2eea8..c183a196dd1b86fdcb2d89e15c3bf9c8b8f74eca 100644
--- a/ui/aura/window_tree_host_platform.cc
+++ b/ui/aura/window_tree_host_platform.cc
@@ -11,6 +11,7 @@
 #include "ui/gfx/screen.h"
 
 #if defined(OS_ANDROID)
+#include "ui/aura/client/aura_constants.h"
 #include "ui/platform_window/android/platform_window_android.h"
 #endif
 
@@ -71,6 +72,16 @@ gfx::AcceleratedWidget WindowTreeHostPlatform::GetAcceleratedWidget() {
 }
 
 void WindowTreeHostPlatform::ShowImpl() {
+#if defined(OS_ANDROID)
+  JNIEnv* env = base::android::AttachCurrentThread();
+  jobject activity = window()->GetProperty(
+      aura::client::kActivityForRootWindow);
+  ui::PlatformWindowAndroid::createForActivity(
+      env,
+      activity,
+      reinterpret_cast<jlong>(window_.get()),
+      reinterpret_cast<jlong>(window_->GetPlatformImeController()));

[sadrul, 2015/11/25 20:59:44]

Curious as to the signature of this function ... why not
PlatformWindowAndroid::AttachToActivity(activity) instead?

[mfomitchev, 2015/11/27 20:57:15]

Done.

+#endif

[sadrul, 2015/11/25 20:59:44]

We shouldn't do this for every call to ::ShowImpl(), just the first one. Right?

If you think there will be additional android-specific changes in
WindowTreeHostPlatform, then it might make sense to have a separate
WindowTreeHostAndroid subclass from WTHPlatform and override ShowImpl().

[mfomitchev, 2015/11/27 20:57:15]

Oops, yes, forgot to fix this, thanks. Done.
I played with creating a new class but we either need to have WTHA duplicate a
bunch of code WTHP, or have a new common abstract superclass for WTHA and
WTHWinOzone, or have some Android ifdefs in WTHP (in addition to WTHA) and I
think the current approach is better than these alternatives.

   window_->Show();
 }