Implement the new Photo picker, part one.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 8c7f49e3a1e63fc8708f85d6882c18d1026139e0..8c02a9c328cf611f4da8fb5d5a87f7165a5443f3 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -99139,6 +99139,7 @@ from previous Chrome versions.
   <int value="-938178614" label="enable-suggestions-with-substring-match"/>
   <int value="-933316841" label="enable-permissions-blacklist"/>
   <int value="-926422468" label="disable-embedded-shared-worker"/>
+  <int value="-924582104" label="enable-new-photo-picker"/>

[Michael van Ouwerkerk, 2017/03/14 15:57:27]

Looks like the test wants something a little different:
C  238.352s Main  [FAIL] AboutFlagsHistogramTest.CheckHistograms:
C  238.352s Main  [ RUN      ] AboutFlagsHistogramTest.CheckHistograms
C  238.352s Main  ../../chrome/browser/about_flags_unittest.cc:304: Failure
C  238.352s Main  Value of: enum_entry != histograms_xml_switches_ids.end() &&
enum_entry->first == flag
C  238.352s Main    Actual: false
C  238.352s Main  Expected: true
C  238.352s Main  histograms.xml enum LoginCustomFlags doesn't contain switch
'NewPhotoPicker:disabled' (value=1960169775 expected). Consider adding entry:
C  238.352s Main    <int value="1960169775" label="NewPhotoPicker:disabled"/>
C  238.352s Main  ../../chrome/browser/about_flags_unittest.cc:304: Failure
C  238.352s Main  Value of: enum_entry != histograms_xml_switches_ids.end() &&
enum_entry->first == flag
C  238.352s Main    Actual: false
C  238.352s Main  Expected: true
C  238.352s Main  histograms.xml enum LoginCustomFlags doesn't contain switch
'NewPhotoPicker:enabled' (value=1928407249 expected). Consider adding entry:
C  238.352s Main    <int value="1928407249" label="NewPhotoPicker:enabled"/>
C  238.352s Main  [  FAILED  ] AboutFlagsHistogramTest.CheckHistograms (321 ms)
C  238.352s Main  [----------] 1 test from AboutFlagsHistogramTest (321 ms
total)

[Finnur, 2017/03/15 13:25:07]

Heh, yeah. I noticed this too late yesterday. It is a case of me getting the
test to work with the about_flags.cc I had, and then changing about_flags.cc. :)

   <int value="-918900957" label="AutofillCreditCardAssist:disabled"/>
   <int value="-918618075" label="enable-service-worker"/>
   <int value="-914210146" label="enable-web-based-signin"/>