Revert "Revert "Make OpenJDK 8 the default""

Reapply the switch to JDK 8 on aosp/master.

This reverts commit 85bddfdedffb425d85657314591a57191113806b.

Change-Id: If2e8733ba78b007d37914c0512cd6be1bd4c1e69
diff --git a/core/droiddoc.mk b/core/droiddoc.mk
index f791884..1b65611 100644
--- a/core/droiddoc.mk
+++ b/core/droiddoc.mk
@@ -209,7 +209,7 @@
                 \@$(PRIVATE_SRC_LIST_FILE) \
                 -J-Xmx1024m \
                 -XDignore.symbol.file \
-                $(if $(EXPERIMENTAL_USE_JAVA8),-Xdoclint:none) \
+                $(if $(LEGACY_USE_JAVA7),,-Xdoclint:none) \
                 $(PRIVATE_PROFILING_OPTIONS) \
                 $(addprefix -classpath ,$(PRIVATE_CLASSPATH)) \
                 $(addprefix -bootclasspath ,$(PRIVATE_BOOTCLASSPATH)) \
diff --git a/core/main.mk b/core/main.mk
index 32b0b39..14594e7 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -144,7 +144,7 @@
 # Include the google-specific config
 -include vendor/google/build/config.mk
 
-VERSION_CHECK_SEQUENCE_NUMBER := 5
+VERSION_CHECK_SEQUENCE_NUMBER := 6
 -include $(OUT_DIR)/versions_checked.mk
 ifneq ($(VERSION_CHECK_SEQUENCE_NUMBER),$(VERSIONS_CHECKED))
 
@@ -180,19 +180,19 @@
 java_version_str := $(shell unset _JAVA_OPTIONS && java -version 2>&1)
 javac_version_str := $(shell unset _JAVA_OPTIONS && javac -version 2>&1)
 
-# Check for the correct version of java, should be 1.7 by
-# default, and 1.8 if EXPERIMENTAL_USE_JAVA8 is set
-ifneq ($(EXPERIMENTAL_USE_JAVA8),)
+# Check for the correct version of java, should be 1.8 by
+# default and only 1.7 if LEGACY_USE_JAVA7 is set.
+ifeq ($(LEGACY_USE_JAVA7),) # if LEGACY_USE_JAVA7 == ''
 required_version := "1.8.x"
 required_javac_version := "1.8"
 java_version := $(shell echo '$(java_version_str)' | grep '[ "]1\.8[\. "$$]')
 javac_version := $(shell echo '$(javac_version_str)' | grep '[ "]1\.8[\. "$$]')
-else # default
+else
 required_version := "1.7.x"
 required_javac_version := "1.7"
 java_version := $(shell echo '$(java_version_str)' | grep '^java .*[ "]1\.7[\. "$$]')
 javac_version := $(shell echo '$(javac_version_str)' | grep '[ "]1\.7[\. "$$]')
-endif # if EXPERIMENTAL_USE_JAVA8
+endif # if LEGACY_USE_JAVA7 == ''
 
 ifeq ($(strip $(java_version)),)
 $(info ************************************************************)
@@ -210,7 +210,7 @@
 
 # Check for the current JDK.
 #
-# For Java 1.7, we require OpenJDK on linux and Oracle JDK on Mac OS.
+# For Java 1.7/1.8, we require OpenJDK on linux and Oracle JDK on Mac OS.
 requires_openjdk := false
 ifeq ($(BUILD_OS),linux)
 requires_openjdk := true