Add documentation with Xcode IDE information

This is not meant to be an exhastive document, but rather a starting
point to help describe how to best use the Xcode IDE.

TBR=noyau@chromium.org

Bug: None
Change-Id: I821dba060353220c1f93cd49dd12dcd74aeaf790
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2188519Reviewed-by: Mike Dougherty <michaeldo@chromium.org>
Commit-Queue: Mike Dougherty <michaeldo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#766549}

docs/ios/build_instructions.md

@@ -76,6 +76,8 @@ build directories under `out` for Release and Debug device and simulator
 builds, and generates an appropriate Xcode workspace
 (`out/build/all.xcworkspace`) as well.
 
+More information about [developing with Xcode](xcode_tips.md).
+
 You can customize the build by editing the file `$HOME/.setup-gn` (create it if
 it does not exist).  Look at `src/ios/build/tools/setup-gn.config` for
 available configuration options.
@@ -91,9 +93,11 @@ $ autoninja -C out/Debug-iphonesimulator gn_all
 (`autoninja` is a wrapper that automatically provides optimal values for the
 arguments passed to `ninja`.)
 
-Note: you need to run `setup-gn.py` script every time one of the `BUILD.gn`
-file is updated (either by you or after rebasing). If you forget to run it,
-the list of targets and files in the Xcode solution may be stale.
+Note: The `setup-gn.py` script needs to run every time one of the `BUILD.gn`
+files is updated (either by you or after rebasing). If you forget to run it,
+the list of targets and files in the Xcode solution may be stale. You can run
+the script directly or use either `gclient sync` or `gclient runhooks` which
+will run `setup-gn.py` for you as part of the update hooks.
 
 You can also follow the manual instructions on the
 [Mac page](../mac_build_instructions.md), but make sure you set the

docs/ios/xcode_tips.md

+# Developing Chrome for iOS with the Xcode IDE
+
+This document contains notes used during a presentation about how to use Xcode
+to develop Chrome for iOS.
+
+## Background
+
+### .xcworkspace and .xcproject
+
+*   Generated from BUILD.gn files.
+*   Don't make changes to it as it is a "fake" representation of the project
+    -   changes will not be committed
+    -   changes will be overwritten without warning
+*   Modify BUILD files instead
+*   Added BUILD.gn files/`source_sets` need to be referenced from other ones as
+    a `dep` in order for it to be shown in xcode.
+
+### Adding new files
+
+*   Create new files with `tools/boilerplate.py`
+*   Add files to BUILD.gn `mate ios/chrome/...BUILD.gn`
+*   Add new source_set target as a dep of another target
+*   Execute `gclient runhooks` or `gclient sync`
+
+### Simulators
+
+*   Simulators build for Mac architecture, not emulators. Fast, generally good
+    for most development
+*   To run on device, need provisioning profiles and certificate
+
+## Xcode
+
+*   Project location is `src/out/build/`, open `all.workspace`
+*   Choose "Automatically generate targets" after a `gclient sync`
+*   Start typing while dropdowns are presented to filter the displayed items
+
+### Targets
+
+*   `chrome' is the main application target
+*   `ios_web_shell` and `ios_web_view_shell` test lower level of application
+
+### Tests
+
+*   Unittests/Inttests
+    -   Add flags to specify tests to run (Option-Click on unittest target name,
+        select Run from left panel, add to "Arguments Passed on Launch")
+    -   `gtest_filter=TestClass.*`
+    -   `gtest_repeat=20`
+    -   Full list of options available by sending an unknown option
+
+*   EarlGrey
+    -   EG1 deprecated
+    -   EG2 are current UI tests
+        -   A separate "test" process communicates with "the app".
+        -   EDO is term for "distant object" on "the other side".
+        -   egtest files can run under both EG1 and EG2 with correct setup in
+            BUILD.gn because the layer of helpers encapsulate the necessary
+            differences.