Bug 1552286 - Move back GeckoJavaSampler to GeckoView and enable for it and fennec r=nalexander,gerald

Bug 1303806 moved `GeckoJavaSampler` to be Fennec-only as part of a general push
to slim GeckoView down.  But there is no reason to restrict to Fennec and it is useful
for other non-Fennec GeckoView vehicles.

This patch moves the `GeckoJavaSampler` inside `geckoview` and changes profiler
code to make Java sampling work in both GeckoView and Fennec.

Depends on D33522

Differential Revision: https://phabricator.services.mozilla.com/D33502

--HG--
rename : mobile/android/base/java/org/mozilla/gecko/GeckoJavaSampler.java => mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoJavaSampler.java
extra : moz-landing-system : lando

tools/profiler/core/platform.cpp

@@ -87,8 +87,8 @@
 #endif
 
 #if defined(GP_OS_android)
-#  include "FennecJNINatives.h"
-#  include "FennecJNIWrappers.h"
+#  include "GeneratedJNINatives.h"
+#  include "GeneratedJNIWrappers.h"
 #endif
 
 // Win32 builds always have frame pointers, so FramePointerStackWalk() always
@@ -462,12 +462,6 @@ class ActivePS {
     // Filter out any features unavailable in this platform/configuration.
     aFeatures &= AvailableFeatures();
 
-#if defined(GP_OS_android)
-    if (!jni::IsFennec()) {
-      aFeatures &= ~ProfilerFeature::Java;
-    }
-#endif
-
     // Always enable ProfilerFeature::Threads if we have a filter, because
     // users sometimes ask to filter by a list of threads but forget to
     // explicitly specify ProfilerFeature::Threads.
@@ -2892,7 +2886,7 @@ void profiler_init(void* aStackTop) {
 #endif
 
 #if defined(GP_OS_android)
-    if (jni::IsFennec()) {
+    if (jni::IsAvailable()) {
       GeckoJavaSampler::Init();
     }
 #endif