XFA: clang-format all pdfium code.

No behavior change.

Generated by:
  find . -name '*.cpp' -o -name '*.h' | \
  grep -E -v 'third_party|thirdparties|lpng_v163|tiff_v403' | \
  xargs ../../buildtools/mac/clang-format -i
Then manually merged https://codereview.chromium.org/1269223002/

See thread "tabs vs spaces" on pdfium@googlegroups.com for discussion.

BUG=none
diff --git a/public/fpdf_flatten.h b/public/fpdf_flatten.h
index 3ae3cd5..5496846 100644
--- a/public/fpdf_flatten.h
+++ b/public/fpdf_flatten.h
@@ -10,28 +10,33 @@
 #include "fpdfview.h"
 
 // Result codes.
-#define FLATTEN_FAIL            0   // Flatten operation failed.
-#define FLATTEN_SUCCESS         1   // Flatten operation succeed.
-#define FLATTEN_NOTHINGTODO     2   // There is nothing to be flattened.
+#define FLATTEN_FAIL 0         // Flatten operation failed.
+#define FLATTEN_SUCCESS 1      // Flatten operation succeed.
+#define FLATTEN_NOTHINGTODO 2  // There is nothing to be flattened.
 
 // Flags.
-#define FLAT_NORMALDISPLAY     0
-#define FLAT_PRINT             1
+#define FLAT_NORMALDISPLAY 0
+#define FLAT_PRINT 1
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 // Function: FPDFPage_Flatten
-//          Make annotations and form fields become part of the page contents itself.
+//          Make annotations and form fields become part of the page contents
+//          itself.
 // Parameters:
 //          page  - Handle to the page, as returned by FPDF_LoadPage().
-//          nFlag - Intended use of the flattened result: 0 for normal display, 1 for printing.
+//          nFlag - Intended use of the flattened result: 0 for normal display,
+//          1 for printing.
 // Return value:
-//          Either FLATTEN_FAIL, FLATTEN_SUCCESS, or FLATTEN_NOTHINGTODO (see above).
+//          Either FLATTEN_FAIL, FLATTEN_SUCCESS, or FLATTEN_NOTHINGTODO (see
+//          above).
 // Comments:
-//          Currently, all failures return FLATTEN_FAIL, with no indication for the reason
-//          for the failure. The method does not support flattening any dynamic XFA fields.
+//          Currently, all failures return FLATTEN_FAIL, with no indication for
+//          the reason
+//          for the failure. The method does not support flattening any dynamic
+//          XFA fields.
 DLLEXPORT int STDCALL FPDFPage_Flatten(FPDF_PAGE page, int nFlag);
 
 #ifdef __cplusplus