Remove duplicated lines in Android Build Instruction

docs/android_build_instructions.md

 # Android Build Instructions
 
 [TOC]
 
 ## Prerequisites
 
 A Linux build machine capable of building [Chrome for
 Linux](https://chromium.googlesource.com/chromium/src/+/master/docs/linux_build_instructions_prerequisites.md).
 Other (Mac/Windows) platforms are not supported for Android.
 
@@ skipping 101 matching lines @@
 ```
 target_os = "android"
 target_cpu = "arm"  # (default)
 is_debug = true  # (default)
 
 # Other args you may want to set:
 is_component_build = true
 is_clang = true
 symbol_level = 1  # Faster build with fewer symbols. -g1 rather than -g2
 enable_incremental_javac = true  # Much faster; experimental
-symbol_level = 1 # Faster build with fewer symbols. -g1 rather than -g2
-enable_incremental_javac = true # Much faster; experimental
 ```
 
 You can also specify `target_cpu` values of "x86" and "mipsel". Re-run
 gn args on that directory to edit the flags in the future. See the [GN
 build
 configuration](https://www.chromium.org/developers/gn-build-configuration)
 page for other flags you may want to set.
 
 ### Install build dependencies
 
@@ skipping 213 matching lines @@
 release of Chrome for Android (v25+) you can do the following steps.
 Note that in order to get your changes into the official release, you'll
 need to send your change for a codereview using the regular process for
 committing code to chromium.
 
 1.  Open Chrome on your Android device and visit chrome://version
 2.  Copy down the id listed next to "Build ID:"
 3.  Go to
     [http://storage.googleapis.com/chrome-browser-components/BUILD\_ID\_FROM\_STEP\_2/index.html](http://storage.googleapis.com/chrome-browser-components/BUILD_ID_FROM_STEP_2/index.html)
 4.  Download the listed files and follow the steps in the README.