Bug 1596769 - Fix broken WebRender capture on Windows r=kvark

On Windows, save the Ctrl-Shift-3 capture to the user's local app data
to make sure we have write permissions.
Verified with ./mach run + capture => saved to C:\Users\...\AppData\Local\wr-capture

Differential Revision: https://phabricator.services.mozilla.com/D53208

--HG--
extra : moz-landing-system : lando

Cargo.lock

@@ -4220,6 +4220,7 @@ dependencies = [
  "bincode 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-foundation 0.6.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "core-graphics 0.17.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "dirs 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "dwrote 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "euclid 0.20.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "foreign-types 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)",

gfx/webrender_bindings/Cargo.toml

@@ -28,6 +28,7 @@ features = ["capture", "serialize_program"]
 
 [target.'cfg(target_os = "windows")'.dependencies]
 dwrote = "0.9"
+dirs = "1.0"
 
 [target.'cfg(target_os = "macos")'.dependencies]
 core-foundation = "0.6"

gfx/webrender_bindings/src/bindings.rs

@@ -2007,6 +2007,13 @@ pub extern "C" fn wr_api_capture(
         }
     }
 
+	#[cfg(target_os = "windows")]
+	{
+		if let Some(storage_path) = dirs::data_local_dir() {
+			path = PathBuf::from(storage_path).join(path);
+		}
+	}
+
     // Increment the extension until we find a fresh path
     while path.is_dir() {
         let count: u32 = path.extension()