Split playbacktests mobile_test into multiple version-dependent test targets.

MobileHarness allocates random devices for each test and repeats tests up to 5 times to
account for spurious test failures. Some of our tests automatically pass for SDK versions
below a certain threshold. Thus, even if such a version-guarded test would always fail,
the MobileHarness test is likely to succeed as it only needs one random allocation to a
device with a lower SDK version.

To prevent this behaviour and to make sure all tests are actually run, the mobile_test
target is split into multiple targets one for each minimum SDK version.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=172447046

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/CommonEncryptionDrmTest.java

@@ -67,7 +67,7 @@ public final class CommonEncryptionDrmTest extends ActivityInstrumentationTestCa
     super.tearDown();
   }
 
-  public void testCencSchemeType() {
+  public void testCencSchemeTypeV18() {
     if (Util.SDK_INT < 18) {
       // Pass.
       return;
@@ -75,7 +75,7 @@ public final class CommonEncryptionDrmTest extends ActivityInstrumentationTestCa
     testRunner.setStreamName("test_widevine_h264_scheme_cenc").setManifestUrl(URL_cenc).run();
   }
 
-  public void testCbc1SchemeType() {
+  public void testCbc1SchemeTypeV25() {
     if (Util.SDK_INT < 25) {
       // cbc1 support was added in API 24, but it is stable from API 25 onwards.
       // See [internal: b/65634809].
@@ -85,7 +85,7 @@ public final class CommonEncryptionDrmTest extends ActivityInstrumentationTestCa
     testRunner.setStreamName("test_widevine_h264_scheme_cbc1").setManifestUrl(URL_cbc1).run();
   }
 
-  public void testCbcsSchemeType() {
+  public void testCbcsSchemeTypeV25() {
     if (Util.SDK_INT < 25) {
       // cbcs support was added in API 24, but it is stable from API 25 onwards.
       // See [internal: b/65634809].
@@ -95,7 +95,7 @@ public final class CommonEncryptionDrmTest extends ActivityInstrumentationTestCa
     testRunner.setStreamName("test_widevine_h264_scheme_cbcs").setManifestUrl(URL_cbcs).run();
   }
 
-  public void testCensSchemeType() {
+  public void testCensSchemeTypeV25() {
     // TODO: Implement once content is available. Track [internal: b/31219813].
   }
 

playbacktests/src/androidTest/java/com/google/android/exoplayer2/playbacktests/gts/DashWidevineOfflineTest.java

@@ -89,7 +89,7 @@ public final class DashWidevineOfflineTest extends ActivityInstrumentationTestCa
 
   // Offline license tests
 
-  public void testWidevineOfflineLicense() throws Exception {
+  public void testWidevineOfflineLicenseV22() throws Exception {
     if (Util.SDK_INT < 22) {
       return; // Pass.
     }
@@ -101,7 +101,7 @@ public final class DashWidevineOfflineTest extends ActivityInstrumentationTestCa
     Assert.assertNotNull(offlineLicenseKeySetId);
   }
 
-  public void testWidevineOfflineReleasedLicense() throws Throwable {
+  public void testWidevineOfflineReleasedLicenseV22() throws Throwable {
     if (Util.SDK_INT < 22) {
       return; // Pass.
     }
@@ -127,7 +127,7 @@ public final class DashWidevineOfflineTest extends ActivityInstrumentationTestCa
     }
   }
 
-  public void testWidevineOfflineExpiredLicense() throws Exception {
+  public void testWidevineOfflineExpiredLicenseV22() throws Exception {
     if (Util.SDK_INT < 22) {
       return; // Pass.
     }
@@ -152,7 +152,7 @@ public final class DashWidevineOfflineTest extends ActivityInstrumentationTestCa
     testRunner.run();
   }
 
-  public void testWidevineOfflineLicenseExpiresOnPause() throws Exception {
+  public void testWidevineOfflineLicenseExpiresOnPauseV22() throws Exception {
     if (Util.SDK_INT < 22) {
       return; // Pass.
     }