Rolls forward https://github.com/flutter/flutter/pull/166717.
Does not copy the `README` or `DEPS` files, and instead uses synthetic
scratch files.
These files can change, so we can't possibly know how to hash them
consistently.
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Reverts: flutter/flutter#166717
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Initiated by: matanlurey
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Reason for reverting: Broke tree on
[postsubmit](https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8718108088961866849/+/u/test:_run_suite_safari-dart2js-canvaskit-engine/stdout)
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Original PR Author: jtmcdole
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Reviewed By: {matanlurey}
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This change reverts the following previous change:
1. Calculate the hash in only two places: `content_aware_hash.{ps1|sh}`
2. Call this from the workflow
3. Eventually call this from `update_engine_version.{ps1|sh}`
The files of import:
* `DEPS`: tracks third party dependencies related to building the engine
* `engine`: all the code in the engine folder
* `bin/internal/content_aware_hash.ps1`: script for calculating the hash
on windows
* `bin/internal/content_aware_hash.sh`: script for calculating the hash
on mac/linux
* `.github/workflows/content-aware-hash.yml`: github action for CI/CD
hashing
Tested on windows and mac:
```shell
PS C:\src\flutter> C:\src\flutter\bin\internal\content_aware_hash.ps1
c24231e276e0719738e175e0622e040ad21a7012
```
```shell
❯ ~/src/flutter/bin/internal/content_aware_hash.sh
c24231e276e0719738e175e0622e040ad21a7012
```
<!-- end_revert_body -->
Co-authored-by: auto-submit[bot] <flutter-engprod-team@google.com>
1. Calculate the hash in only two places: `content_aware_hash.{ps1|sh}`
2. Call this from the workflow
3. Eventually call this from `update_engine_version.{ps1|sh}`
The files of import:
* `DEPS`: tracks third party dependencies related to building the engine
* `engine`: all the code in the engine folder
* `bin/internal/content_aware_hash.ps1`: script for calculating the hash
on windows
* `bin/internal/content_aware_hash.sh`: script for calculating the hash
on mac/linux
* `.github/workflows/content-aware-hash.yml`: github action for CI/CD
hashing
Tested on windows and mac:
```shell
PS C:\src\flutter> C:\src\flutter\bin\internal\content_aware_hash.ps1
c24231e276e0719738e175e0622e040ad21a7012
```
```shell
❯ ~/src/flutter/bin/internal/content_aware_hash.sh
c24231e276e0719738e175e0622e040ad21a7012
```