Fixit: Add PRESUBMIT check for TimeXXX::To/FromInternalValue().

The fix-it to remove the uses of To/FromInternalValue() is underway.
This change adds a PRESUBMIT warning (BANNED_CPP_FUNCTIONS) and
base/time/time.h header comments, to avoid having new code use these
deprecated functions.

The intention is for this change to be short-lived, and removed once
the deprecated functions are removed from the time classes.

One fault in the check: Since the script can only do regexp matching,
it's impossible to check that the ToInternalValue() method is being
called on one of the TimeXXX types. However, there are relatively few
non-TimeXXX types that have a ToInternalValue() method. Therefore, it
should be rare for the script to trigger a warning erroneously (and
this would be easy to bypass, anyway).

Bug: 634507
Change-Id: I48d75435703771107c87935cb3ea90a5a956989e
Reviewed-on: https://chromium-review.googlesource.com/577980Reviewed-by: Paweł Hajdan Jr. <phajdan.jr@chromium.org>
Commit-Queue: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#488505}

PRESUBMIT.py

@@ -369,6 +369,21 @@ _BANNED_CPP_FUNCTIONS = (
       False,
       (),
     ),
+    (
+      r'/(Time(|Delta|Ticks)|ThreadTicks)::FromInternalValue|ToInternalValue',
+      (
+        'base::TimeXXX::FromInternalValue() and ToInternalValue() are',
+        'deprecated (http://crbug.com/634507). Please avoid converting away',
+        'from the Time types in Chromium code, especially if any math is',
+        'being done on time values. For interfacing with platform/library',
+        'APIs, use FromMicroseconds() or InMicroseconds(), or one of the other',
+        'type converter methods instead. For faking TimeXXX values (for unit',
+        'testing only), use TimeXXX() + TimeDelta::FromMicroseconds(N). For',
+        'other use cases, please contact base/time/OWNERS.',
+      ),
+      False,
+      (),
+    ),
     (
       'CallJavascriptFunctionUnsafe',
       (

base/time/time.h

@@ -129,6 +129,8 @@ class BASE_EXPORT TimeDelta {
   // when deserializing a |TimeDelta| structure, using a value known to be
   // compatible. It is not provided as a constructor because the integer type
   // may be unclear from the perspective of a caller.
+  //
+  // DEPRECATED - Do not use in new code. http://crbug.com/634507
   static TimeDelta FromInternalValue(int64_t delta) { return TimeDelta(delta); }
 
   // Returns the maximum time delta, which should be greater than any reasonable
@@ -145,6 +147,8 @@ class BASE_EXPORT TimeDelta {
   // use this and do arithmetic on it, as it is more error prone than using the
   // provided operators.
   // For serializing, use FromInternalValue to reconstitute.
+  //
+  // DEPRECATED - Do not use in new code. http://crbug.com/634507
   int64_t ToInternalValue() const { return delta_; }
 
   // Returns the magnitude (absolute value) of this TimeDelta.
@@ -355,6 +359,8 @@ class TimeBase {
   // For serializing only. Use FromInternalValue() to reconstitute. Please don't
   // use this and do arithmetic on it, as it is more error prone than using the
   // provided operators.
+  //
+  // DEPRECATED - Do not use in new code. http://crbug.com/634507
   int64_t ToInternalValue() const { return us_; }
 
   TimeClass& operator=(TimeClass other) {
@@ -407,6 +413,8 @@ class TimeBase {
   // when deserializing a |TimeClass| structure, using a value known to be
   // compatible. It is not provided as a constructor because the integer type
   // may be unclear from the perspective of a caller.
+  //
+  // DEPRECATED - Do not use in new code. http://crbug.com/634507
   static TimeClass FromInternalValue(int64_t us) { return TimeClass(us); }
 
  protected: