[Android] Roll android_tools to Android M SDK.

content/public/android/BUILD.gn

Index: content/public/android/BUILD.gn
diff --git a/content/public/android/BUILD.gn b/content/public/android/BUILD.gn
index 0c80b4dfbcd03631c2d8616e52b4ef11e9afb5f8..cd610f9a81639863f668e87ccb69df4e2aba1e36 100644
--- a/content/public/android/BUILD.gn
+++ b/content/public/android/BUILD.gn
@@ -52,10 +52,6 @@ android_library("content_java") {
     #"//content:content_common",
   ]
 
-  if (android_sdk_version != "M") {
-    deps += [ "//third_party/android_tools:preview_java_sources" ]
-  }
-
   srcjar_deps = [
     ":common_aidl",
     ":content_public_android_java_enums_srcjar",
@@ -183,6 +179,7 @@ android_library("content_javatests") {
     "//net/android:net_java",
     "//net/android:net_java_test_support",
     "//third_party/android_tools:android_support_v13_java",
+    "//third_party/android_tools:legacy_http_javalib",
     "//third_party/mojo/src/mojo/public/interfaces/bindings/tests:test_interfaces_java",
     "//third_party/mojo/src/mojo/public/java:bindings",
     "//third_party/mojo/src/mojo/public/java:system",