Reland: "Make javac warnings errors for WebRTC targets."

This reverts commit 2bad72a27329ff30ceb9479253f5eb3d21888d25.

Reason for revert: Fixing downstream projects (take 2).

Original change's description:
> Reland "Revert "Make javac warnings errors for WebRTC targets.""
> 
> This is a reland of 098d24c3c18f4b1fd043d7ba716d7601f0ce2b74
> Original change's description:
> > Revert "Make javac warnings errors for WebRTC targets."
> > 
> > This reverts commit 19b761403c3522902d69d61179f4d184e3632f79.
> > 
> > Reason for revert: Breaking internal builds
> > 
> > Original change's description:
> > > Make javac warnings errors for WebRTC targets.
> > > 
> > > Adds new rtc_* templates for Android targets to allow specifying
> > > default values that affect WebRTC targets.
> > > 
> > > Bug: webrtc:6597
> > > Change-Id: Ie529bfc8500d1e785b8a59dba7078b5f88ccfcd1
> > > Reviewed-on: https://webrtc-review.googlesource.com/15103
> > > Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
> > > Commit-Queue: Sami Kalliomäki <sakal@webrtc.org>
> > > Cr-Commit-Position: refs/heads/master@{#20567}
> > 
> TBR=phoglund@webrtc.org,sakal@webrtc.org
> > 
> > Change-Id: I6d3ff5604b3d4307765d3a65adb783f89fcc974c
> > No-Presubmit: true
> > No-Tree-Checks: true
> > No-Try: true
> > Bug: webrtc:6597
> > Reviewed-on: https://webrtc-review.googlesource.com/20740
> > Reviewed-by: Lu Liu <lliuu@webrtc.org>
> > Commit-Queue: Lu Liu <lliuu@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#20571}
> 
> Bug: webrtc:6597
> Change-Id: Icfb5ded46ce76b674bae67bfa02054b4ec52bb0f
> Reviewed-on: https://webrtc-review.googlesource.com/20800
> Commit-Queue: Edward Lemur <ehmaldonado@webrtc.org>
> Reviewed-by: Edward Lemur <ehmaldonado@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20577}

TBR=phoglund@webrtc.org,ehmaldonado@webrtc.org,mbonadei@webrtc.org,sakal@webrtc.org,lliuu@webrtc.org

Change-Id: Id3713c1885318741711987ae642a269a9ca5bb85
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:6597
Reviewed-on: https://webrtc-review.googlesource.com/18441
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20588}
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 400efb6..bc9b929 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -1089,15 +1089,12 @@
 }
 
 if (is_android) {
-  android_library("base_java") {
+  rtc_android_library("base_java") {
     java_files = [
       "java/src/org/webrtc/ContextUtils.java",
       "java/src/org/webrtc/Logging.java",
       "java/src/org/webrtc/Size.java",
       "java/src/org/webrtc/ThreadUtils.java",
     ]
-
-    # TODO(sakal): Fix build hooks crbug.com/webrtc/8148
-    no_build_hooks = true
   }
 }