jni: Forbid inappropriate JNI parameter conversions.

jni: Forbid inappropriate JNI parameter conversions.

Don't allow JavaParamRefs to be used to construct ScopedJavaLocalRefs.
This leads to incorrect reference handling behaviour, since parameters
are not allowed to be deleted. Instead code should simply pass the
JavaParamRef by reference; functions should be taking "const JavaRef&"
for input which is compatible.

Fix the cases in the code where this conversion is currently being
relied upon.

BUG=506850
Committed: https://crrev.com/a8dd7a4e29d91d91c2b5e3e97062f5945737c050
Cr-Commit-Position: refs/heads/master@{#347923}

[Torne, 2015-09-04 12:52:37]

torne@chromium.org changed reviewers:
+ kelvinp@chromium.org, mef@chromium.org, rmcilroy@chromium.org,
yfriedman@chromium.org

[Torne, 2015-09-04 12:52:38]

rmcilroy: general review, base/android/scoped_java_ref.h
yfriedman: chrome/, content/
kelvinp: remoting/
mef: components/cronet/

[Torne, 2015-09-04 14:02:02]

torne@chromium.org changed reviewers:
+ gunsch@chromium.org, sky@chromium.org

[Torne, 2015-09-04 14:02:02]

+gunsch: chromecast/
+sky: mojo/

[rmcilroy, 2015-09-04 14:06:23]

lgtm.

[mef, 2015-09-04 14:15:22]

components/cronet lgtm

[Yaron, 2015-09-04 14:23:23]

lgtm

[sky, 2015-09-04 15:00:46]

LGTM

[Torne, 2015-09-08 09:51:03]

torne@chromium.org changed reviewers:
+ halliwell@chromium.org, lambroslambrou@chromium.org

[Torne, 2015-09-08 09:51:03]

+lambroslambrou: remoting/
+halliwell: chromecast/

[gunsch, 2015-09-08 15:06:51]

chromecast/ lgtm

(sorry for delay, was out sick Friday, US holiday yesterday)

[Torne, 2015-09-08 15:26:42]

On 2015/09/08 15:06:51, gunsch wrote:
> chromecast/ lgtm
> 
> (sorry for delay, was out sick Friday, US holiday yesterday)

Sorry, totally forgot about the US holiday :)

[Lambros, 2015-09-08 20:58:33]

remoting/ lgtm

[Torne, 2015-09-09 09:41:29]

The CQ bit was checked by torne@chromium.org

[commit-bot: I haz the power, 2015-09-09 09:41:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1326763009/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1326763009/20001

[commit-bot: I haz the power, 2015-09-09 13:53:15]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-09 13:54:10]

Patchset 2 (id:??) landed as
https://crrev.com/a8dd7a4e29d91d91c2b5e3e97062f5945737c050
Cr-Commit-Position: refs/heads/master@{#347923}