Add Contributing to Skia section of docs

site/dev/contrib/submit.md

+How to submit a patch
+=====================
+
+
+Making changes
+--------------
+
+First create a branch for your changes:
+
+~~~~
+$ git checkout --track origin/master -b my_feature master
+~~~~
+
+After making your changes, create a commit
+
+~~~~
+$ git add [file1] [file2] ...
+$ git commit
+~~~~
+
+If your branch gets out of date, you will need to update it:
+
+~~~~
+$ git pull --rebase
+$ gclient sync
+~~~~
+
+
+Adding a unit test
+------------------
+
+If you are willing to change Skia codebase, it's nice to add a test at the same time. Skia has a simple unittest framework so you can add a case to it.
+
+Test code is located under the 'tests' directory. Assuming we are adding tests/FooTest.cpp, The test code will look like:
+
+~~~~
+/*
+ * Copyright ........
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Test.h"
+
+DEF_TEST(TestFoo, reporter) {
+   int x = 2 * 3;
+   if (x != 6) {
+       ERRORF(reporter, "x should be 6, but is %d", x);
+       return;
+   }
+   REPORTER_ASSERT(reporter, 1 + 1 == 2);
+}
+~~~~
+
+And we need to add this new file to gyp/tests.gyp. Note that file names are sorted alphabetically.
+
+~~~~
+'sources': [
+  '../tests/AAClipTest.cpp'
+  '../tests/FooTest.cpp',
+  '../tests/XfermodeTest.cpp',
+],
+~~~~
+
+Unit tests are best, but if your change touches rendering and you can't think of an automated way to verify the results, consider writing a GM test or a new page of SampleApp. Also, if your change is the GPU code, you may not be able to write it as part of the standard unit test suite, but there are GPU-specific testing paths you can extend.
+
+
+Submitting a patch
+------------------
+
+For your code to be accepted into the codebase, you must complete the [Individual Contributor License Agreement](http://code.google.com/legal/individual-cla-v1.0.html). You can do this online, and it only takes a minute. If you are contributing on behalf of a corporation, you must fill out the [Corporate Contributor License Agreement](http://code.google.com/legal/corporate-cla-v1.0.html) and send it to us as described on that page. Add your (or your organization's) name and contact info to the AUTHORS file as a part of your CL.
+
+Now that you've made a change and written a test for it, it's ready for the code review! Submit a patch and getting it reviewed is fairly easy with depot tools.
+
+Use git-cl, which comes with [depot tools](http://sites.google.com/a/chromium.org/dev/developers/how-tos/install-depot-tools). For help, run git-cl help.
+
+### Configuring git-cl
+
+Before using any git-cl commands you will need to configure it to point at the correct code review server. This is accomplished with the following command:
+
+~~~~
+git cl config https://skia.googlesource.com/skia/+/master/codereview.settings
+~~~~
+
+### Find a reviewer
+
+Ideally, the reviewer is someone who is familiar with the area of code you are touching. If you have doubts, look at the git blame for the file to see who else has been editing it.
+
+### Uploading changes for review
+
+Skia uses Chromium's code review [site](http://codereview.chromium.org) and the Rietveld open source code review tool.  
+Use git cl to upload your change:
+~~~~
+$ git cl upload 
+~~~~
+
+You may have to enter a Google Account username and password to authenticate yourself to codereview.chromium.org. A free gmail account will do fine, or any other type of Google account.  It does not have to match the email address you configured using git config --global user.email above, but it can.
+
+The command output should include a URL, similar to (https://codereview.chromium.org/111893004/), indicating where your changelist can be reviewed.
+
+### Request review
+
+Go to the supplied URL or go to the code review page and click **Issues created by me**. Select the change you want to submit for review and click **Edit Issue**. Enter at least one reviewer's email address and click **Update Issue**. Now click on **Publish+Mail Comments**, add any optional notes, and send your change off for review. Unless you publish your change, no one will know to look at it.
+
+_Note_: If you don't see editing commands on the review page, click **Log In** in the upper right. _Hint_: You can add -r reviewer@example.com --send-mail to send the email directly when uploading a change in both gcl and git-cl.
+
+
+The review process
+------------------
+
+If you submit a giant patch, or do a bunch of work without discussing it with the relevant people, you may have a hard time convincing anyone to review it!
+
+Please follow the guidelines on how to conduct a code review detailed here: https://code.google.com/p/rietveld/wiki/CodeReviewHelp
+
+Code reviews are an important part of the engineering process. The reviewer will almost always have suggestions or style fixes for you, and it's important not to take such suggestions personally or as a commentary on your abilities or ideas. This is a process where we work together to make sure that the highest quality code gets submitted!
+
+You will likely get email back from the reviewer with comments. Fix these and update the patch set in the issue by uploading again. The upload will explain that it is updating the current CL and ask you for a message explaining the change. Be sure to respond to all comments before you request review of an update.
+
+If you need to update code the code on an already uploaded CL, simply edit the code, commit it again locally, and then run git cl upload again e.g.
+
+~~~~
+echo "" > GOATS
+git add GOATS
+git commit -m 'add newline fix to GOATS'
+git cl upload
+~~~~
+
+Once you're ready for another review, use **Publish+Mail Comments** again to send another notification (it is helpful to tell the review what you did with respect to each of their comments). When the reviewer is happy with your patch, they will say "LGTM" ("Looks Good To Me").
+
+_Note_: As you work through the review process, both you and your reviewers should converse using the code review interface, and send notes using **Publish+Mail Comments**.
+
+Once your commit has gone in, you should delete the branch containing your change:
+
+~~~~
+$ git checkout master
+$ git branch -D my_feature
+~~~~
+
+
+Final Testing
+-------------
+
+Skia's principal downstream user is Chromium, and any change to Skia rendering output can break Chromium. If your change alters rendering in any way, you are expected to test for and alleviate this. (You may be able to find a Skia team member to help you, but the onus remains on each individual contributor to avoid breaking Chrome.
+
+### Evaluating Impact on Chromium
+
+Keep in mind that Skia is rolled daily into Blink and Chromium.  Run local tests and watch canary bots for results to ensure no impact.  If you are submitting changes that will impact layout tests, follow the guides below and/or work with your friendly Skia-Blink engineer to evaluate, rebaseline, and land your changes.
+
+Resources:
+
+[How to land Skia changes that change Blink layout test results](../chrome/layouttest)
+
+If you're changing the Skia API, you may need to make an associated change in Chromium.  If you do, please follow these instructions: [Landing Skia changes which require associated Chrome changes](../chrome/changes)
+
+
+Check in your changes
+---------------------
+
+### Non-Skia-committers
+
+If you already have committer rights, you can follow the directions below to commit your change directly to Skia's repository.
+
+If you don't have committer rights in https://skia.googlesource.com/skia.git ... first of all, thanks for submitting your patch!  We really appreciate these submissions.  Unfortunately, we don't yet have a way for Skia committers to mark a patch as "approved" and thus allow non-committers to commit them.  So instead, please ask a Skia committer to land your patch for you or land using the commit queue.
+
+As part of this process, the Skia committer may create a new codereview containing your patch (perhaps with some small adjustments at her discretion).  If so, you can mark your codereview as "Closed", and update it with a link to the new codereview.
+
+### Skia committers: 
+  *  tips on how to apply the externally provided patch are [here](./patch)
+  *  when landing externally contributed patches, please note the original contributor's identity (and provide a link to the original codereview) in the commit message
+
+git-cl will squash all your commits into a single one with the description you used when you uploaded your change.
+
+~~~~
+git cl land
+~~~~
+or
+~~~~
+git cl land -c 'Contributor Name <email@example.com>'
+~~~~