Plumbing maxTouchPoints for Android.

ui/base/touch/touch_device_android.cc

Index: ui/base/touch/touch_device_android.cc
diff --git a/ui/base/touch/touch_device_android.cc b/ui/base/touch/touch_device_android.cc
index 2b359c0e3dd44e39d669ddd7db8800862342ac9e..1828703291a2cdc979356922eb0b77db7fc1a8ee 100644
--- a/ui/base/touch/touch_device_android.cc
+++ b/ui/base/touch/touch_device_android.cc
@@ -4,23 +4,30 @@
 
 #include "ui/base/touch/touch_device.h"
 
+#include "jni/TouchDevice_jni.h"
+#include "ui/base/touch/touch_device_android_initialization.h"

[Ted C, 2014/03/05 21:14:26]

hmm...this name is a bit odd to me.  I might just use touch_device_android.h.

Or maybe just ifdef the registration method in the base header.

[bokan, 2014/03/05 22:49:20]

Went with the latter.

+
+using namespace base::android;

[Ted C, 2014/03/05 21:14:26]

Since the usage is pretty small, I would leave this out and use base::android 
everywhere.

[bokan, 2014/03/05 22:49:20]

Done.

+
 namespace ui {
 
 bool IsTouchDevicePresent() {
   return true;
 }
 
-// Looks like the best we can do here is detect 1, 2+, or 5+ by
-// feature detecting:
-// FEATURE_TOUCHSCREEN (1),
-// FEATURE_TOUCHSCREEN_MULTITOUCH (2),
-// FEATURE_TOUCHSCREEN_MULTITOUCH_DISTINCT (2+), or
-// FEATURE_TOUCHSCREEN_MULTITOUCH_JAZZHANDS (5+)
-//
-// Probably start from the biggest and detect down the list until we
-// find one that's supported and return its value.
 int MaxTouchPoints() {
-  return kMaxTouchPointsUnknown;
+  JNIEnv* env = AttachCurrentThread();
+  DCHECK(env);

[Ted C, 2014/03/05 21:14:26]

Do we DCHECK any other usages of AttachCurrentThread or GetApplicationContext? 
I'm thinking you can leave them out if no other place checks.

[bokan, 2014/03/05 22:49:20]

Done.

+
+  jobject context = base::android::GetApplicationContext();
+  DCHECK(context);
+
+  jint max_touch_points = Java_TouchDevice_maxTouchPoints(env, context);
+  return static_cast<int>(max_touch_points);
+}
+
+bool RegisterTouchDeviceAndroid(JNIEnv* env) {
+  return RegisterNativesImpl(env);
 }
 
 }  // namespace ui