Roll chromium_revision a12e1e1..0cb2549 (326495:327252)

https://codereview.chromium.org/1051343002 adds a dependency
on Chromium's third_party/junit into base/ which affects our
Android tests that uses that code.

The precompiled JUnit 4.11 JAR file that is only by the
libjingle_peerconnection_java_unittest target on Linux has been
moved to third_party/junit-jar, since it collided with the expected
path for the JUnit dependency mentioned above.
It had to be kept since the Chromium JUnit is only possible to build
when OS==android.

This CL also brings in Mockito and Robolectric, which should be
useful for our Android tests.

Other relevant changes:
* src/buildtools: 3b302fe..15308f4
* src/third_party/libjpeg_turbo: 034e9a9..9e9058b
* src/third_party/libyuv: 32ad6e0..01db3d1
Details: https://chromium.googlesource.com/chromium/src/+/a12e1e1..0cb2549/DEPS

Clang version was not updated in this roll.

BUG=4499
R=phoglund@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/48239004

Cr-Commit-Position: refs/heads/master@{#9113}
diff --git a/.gitignore b/.gitignore
index e173e64..4a6d211 100644
--- a/.gitignore
+++ b/.gitignore
@@ -100,6 +100,7 @@
 /third_party/jsoncpp
 /third_party/jsr-305
 /third_party/junit
+/third_party/junit-jar
 /third_party/libc++
 /third_party/libc++abi
 /third_party/libevent
@@ -113,6 +114,7 @@
 /third_party/libyuv
 /third_party/llvm
 /third_party/llvm-build
+/third_party/mockito
 /third_party/modp_b64
 /third_party/nss
 /third_party/oauth2
@@ -121,6 +123,7 @@
 /third_party/opus
 /third_party/protobuf
 /third_party/requests
+/third_party/robolectric
 /third_party/sqlite
 /third_party/syzygy
 /third_party/usrsctp