[6/N] Add DIR_METADATA files to directories under //content

Generate DIR_METADATA files and remove metadata from OWNERS
files for directories under //content.

R=danakj@chromium.org, jochen@chromium.org, majidvp@chromium.org

Bug: 1113033
Change-Id: I819cce1cfa2d16cafb61b963b26e54647eee61ad
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2543696
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Auto-Submit: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Jochen Eisinger <jochen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#828852}

content/test/portal/DIR_METADATA

+monorail {
+  component: "Blink>Portals"
+}

content/test/portal/OWNERS

 file://third_party/blink/renderer/core/html/portal/OWNERS
-
-# COMPONENT: Blink>Portals

content/test/ppapi/DIR_METADATA

+monorail {
+  component: "Internals>Plugins>Pepper"
+}
+team_email: "pepper-dev@chromium.org"

content/test/ppapi/OWNERS

 bbudge@chromium.org
 raymes@chromium.org
-
-# COMPONENT: Internals>Plugins>Pepper
-# TEAM: pepper-dev@chromium.org

content/utility/speech/DIR_METADATA

+monorail {
+  component: "Internals>Sandbox"
+}

content/utility/speech/OWNERS

 per-file speech_recognition_sandbox_hook_linux.*=file://sandbox/linux/OWNERS
-
-# COMPONENT: Internals>Sandbox

content/web_test/DIR_METADATA

+monorail {
+  component: "Test"
+}

content/web_test/OWNERS

@@ -2,5 +2,3 @@ mkwst@chromium.org
 peter@chromium.org
 danakj@chromium.org
 
-# COMPONENT: Test
-

content/zygote/DIR_METADATA

+monorail {
+  component: "Internals>Sandbox"
+}
+team_email: "security-dev@chromium.org"

content/zygote/OWNERS

 file://sandbox/linux/OWNERS
-
-# TEAM: security-dev@chromium.org
-# COMPONENT: Internals>Sandbox