Update docs/clion.md

- Replaced 'Building, Running, and Debugging' section
  - Previously, this section was incomplete and only described how to
build chromium.
  - Added instructions to run and visually debug as well.
  - Updated build instructions to support debugging.
- Simplified recommended CMakeLists.txt file
- Simplified instructions for creating a desktop entry
- Increased recommended VM option Xmx from 5g to 10g
- Marked optional steps as optional
- Punctuation fixes
- Added link to clion.md to docs/README.md

Change-Id: Id0514b1498517e0c10fafb1a9639aeda44717921
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1976280
Commit-Queue: manuk hovanesian <manukh@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#726546}

docs/README.md

@@ -68,14 +68,15 @@ used when committed.
 
 ### Integrated Development Environment (IDE) Set Up Guides
 *   [Android Studio](android_studio.md) - Android Studio for Android builds
+*   [Atom](atom.md) - Atom multi-platform code editor
+*   [CLion](clion.md) - CLion IDE, supports GUI debugging.
 *   [Eclipse for Android](eclipse.md) - Eclipse for Android
 *   [Eclipse for Linux](linux_eclipse_dev.md) - Eclipse for other platforms
     (This guide was written for Linux, but is probably usable on Windows/MacOS
     as well)
-*   [Qt Creator](qtcreator.md) - Using Qt Creator as an IDE or GUI debugger
-*   [Setting up Visual Studio Code](vscode.md) - Visual Studio Code
 *   [EMACS Notes](emacs.md) - EMACS commands/styles/tool integrations
-*   [Atom](atom.md) - Atom multi-platform code editor
+*   [Qt Creator](qtcreator.md) - Using Qt Creator as an IDE or GUI debugger
+*   [Visual Studio Code](vscode.md) - Visual Studio Code
 
 ### Git
 *   [Git Cookbook](git_cookbook.md) - A collection of git recipes for common

docs/clion.md

@@ -0,0 +1,105 @@
+# CLion Dev
+
+CLion is an IDE
+
+Prerequisite:
+[Checking out and building the chromium code base](README.md#Checking-Out-and-Building)
+
+[TOC]
+
+## Setting up CLion
+1. Install CLion
+    - Googlers only: See
+      [go/intellij-getting-started](https://goto.google.com/intellij-getting-started)
+      for installation and license authentication instructions
+
+1. Run CLion
+1. Increase CLion's memory allocation
+
+    This step will help performance with large projects
+    1. Option 1
+        1. At the startup dialogue, in the bottom right corner, click
+           `Configure`
+        1. Setup `Edit Custom VM Options`:
+            ```
+            -Xss2m
+            -Xms1g
+            -Xmx10g
+            ...
+            ```
+        1. (Optional) Setup `Edit Custom Properties`:
+            ```
+            idea.max.intellisense.filesize=12500
+            ```
+    1. Option 2; 2017 and prior versions may not include the options to setup
+    your `VM Options` and `Properties` in the `configure` menu. Instead:
+        1. `Create New Project`
+        1. `Help` > `Edit Custom VM Options`
+        1. (Optional) `Help` > `Edit Custom Properties`
+
+## Chromium in CLion
+1. Import project
+    - At the startup dialog, select `Import Project` and select your `chromium`
+      directory; this should be the parent directory to `src`. Selecting `src`
+      instead would result in some CLion IDE files appearing in your repository.
+1. (Optional) Modify the `CMakeLists.txt` file
+    1. Open the `CMakeLists.txt` file
+    1. Replace the `include_directories` with the following. This will help
+       with navigating between files.
+       ```
+       include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src)
+       ```
+    1. (Optional) Replace the `add_executable` files to include a single file.
+       Doing this might improve CLion performance. Leaving at least 1 file is
+       required in order for CLion to provide code completion, navigation, etc.
+       The file should now look like:
+       ```
+       cmake_minimum_required(VERSION 3.10)
+       project(chromium)
+
+       set(CMAKE_CXX_STANDARD 14)
+
+       include_directories(${CMAKE_CURRENT_SOURCE_DIR}/src)
+
+       add_executable(chromium src/components/omnibox/browser/document_provider.cc)
+       ```
+
+## Building, Running, and Debugging within CLion
+1. Edit the `custom build targets` settings
+    1. `ctrl+shift+a` > `custom build targets`
+    1. Click the `+` button to create a new target.
+    1. Click the `...` button next to the `Build` field
+    1. Click the `+` button in the new panel
+    1. Configure the fields:
+       ```
+       Program: <absolute path to depot_tools/ninja>
+       Arguments: -C src/out/Default -j 1000 chrome
+       ```
+    1. (Optional) Repeat for Debug or other build configurations.
+1. Create a run configuration
+    1. `Run` > `Edit Configurations`
+    1. Click `+` in the top left and select `Custom Build Application`
+    1. Set the `Target` field to one of the targets configured in step 1
+    1. Click 'Select other` option for the `Executable` field and select the
+    chrome build e.g. `out/Default/chrome`
+    1. (Optional) Repeat for Debug or other build configurations. The built
+    targets and executables should match; i.e. don't build `out/Debug `but
+    execute `out/Default/chrome`.
+1. `Run` > `Run` (`shift+f10`) or `Run` > `Debug` (`shift+f9`) (screenshot)
+    ![debugging screenshot](images/clion_gui_debugging.png)
+
+## Optional Steps
+
+### Create terminal cli or desktop entry
+To make it easier to startup CLion or open individual files:
+1. Open the actions menu (`ctrl+shift+a`)
+1. Type `create desktop entry` and press `enter`
+1. Open the actions menu and enter `create command-line launcher`
+
+### Mark directories as `Library Files`
+To speed up CLion, optionally mark directories such as `src/third_party` as
+`Library Files`
+1. Open the `Project` navigation (`alt+1`)
+1. Select and right click the directories > `Mark directory as` >
+   `Library Files`
+1. See `https://blog.jetbrains.com/clion/2015/12/mark-dir-as/` for more details