feat(screenshot): support out-of-proc capture (#1541)

* feat(screenshot): support out-of-proc capture

Add a `pid` parameter to `sentry__screenshot_capture()` to allow
capturing the windows of a specific process instead of always using the
current process. Passing 0 preserves the existing behavior.

This is needed for the upcoming native backend (#1433), where a daemon
process captures screenshots on behalf of the crashed application.

Partially cherry-picked from 62f1cdb
(#1433)

* Fix lint

---------

Co-authored-by: J-P Nurmi <jpnurmi@gmail.com>

Author: mujacica

src/backends/sentry_backend_breakpad.cpp

@@ -184,7 +184,7 @@ breakpad_backend_callback(const google_breakpad::MinidumpDescriptor &descriptor,
                 sentry_attachment_t *screenshot = sentry__attachment_from_path(
                     sentry__screenshot_get_path(options));
                 if (screenshot
-                    && sentry__screenshot_capture(screenshot->path)) {
+                    && sentry__screenshot_capture(screenshot->path, 0)) {
                     sentry__envelope_add_attachment(envelope, screenshot);
                 }
                 sentry__attachment_free(screenshot);

src/backends/sentry_backend_inproc.c

@@ -1169,7 +1169,7 @@ process_ucontext_deferred(const sentry_ucontext_t *uctx,
                 sentry_attachment_t *screenshot = sentry__attachment_from_path(
                     sentry__screenshot_get_path(options));
                 if (screenshot
-                    && sentry__screenshot_capture(screenshot->path)) {
+                    && sentry__screenshot_capture(screenshot->path, 0)) {
                     sentry__envelope_add_attachment(envelope, screenshot);
                 }
                 sentry__attachment_free(screenshot);

src/screenshot/sentry_screenshot_none.c

@@ -3,7 +3,8 @@
 #include "sentry_core.h"
 
 bool
-sentry__screenshot_capture(const sentry_path_t *UNUSED(path))
+sentry__screenshot_capture(
+    const sentry_path_t *UNUSED(path), uint32_t UNUSED(pid))
 {
     return false;
 }

src/screenshot/sentry_screenshot_windows.c

@@ -153,14 +153,17 @@ calculate_region(DWORD pid, HRGN region)
 }
 
 bool
-sentry__screenshot_capture(const sentry_path_t *path)
+sentry__screenshot_capture(const sentry_path_t *path, uint32_t pid)
 {
 #ifdef SENTRY_PLATFORM_XBOX
     (sentry_path_t *)path;
+    (uint32_t)pid;
     return false;
 #else
+    // Use provided PID, or current process if 0
+    DWORD target_pid = pid ? pid : GetCurrentProcessId();
     HRGN region = CreateRectRgn(0, 0, 0, 0);
-    calculate_region(GetCurrentProcessId(), region);
+    calculate_region(target_pid, region);
 
     RECT box;
     GetRgnBox(region, &box);

src/sentry_screenshot.h

@@ -9,9 +9,13 @@
 /**
  * Captures a screenshot and saves it to the specified path.
  *
+ * @param path The path where the screenshot should be saved.
+ * @param pid The process ID whose windows should be captured (0 = current
+ * process).
+ *
  * Returns true if the screenshot was successfully captured and saved.
  */
-bool sentry__screenshot_capture(const sentry_path_t *path);
+bool sentry__screenshot_capture(const sentry_path_t *path, uint32_t pid);
 
 /**
  * Returns the path where a screenshot should be saved.