Linux: Increase storage size of vmstat data

The linux kernel stores and prints the data associated with /proc/vmstat
as unsigned longs, so increase Chrome's storage of these fields
accordingly.
https://github.com/torvalds/linux/blob/e4fba88d00d21f50239eac7d653027bfaf844296/include/linux/vmstat.h#L25

Review-Url: https://codereview.chromium.org/2188043003
Cr-Commit-Position: refs/heads/master@{#408774}

base/process/process_metrics.h

@@ -296,9 +296,9 @@ struct BASE_EXPORT SystemMemoryInfoKB {
   int dirty;
 
   // vmstats data.
-  int pswpin;
-  int pswpout;
-  int pgmajfault;
+  unsigned long pswpin;
+  unsigned long pswpout;
+  unsigned long pgmajfault;
 #endif  // defined(OS_ANDROID) || defined(OS_LINUX)
 
 #if defined(OS_CHROMEOS)

base/process/process_metrics_linux.cc

@@ -687,12 +687,16 @@ bool ParseProcVmstat(const std::string& vmstat_data,
     if (tokens.size() != 2)
       continue;
 
+    uint64_t val;
+    if (!StringToUint64(tokens[1], &val))
+      continue;
+
     if (tokens[0] == "pswpin") {
-      StringToInt(tokens[1], &meminfo->pswpin);
+      meminfo->pswpin = val;
     } else if (tokens[0] == "pswpout") {
-      StringToInt(tokens[1], &meminfo->pswpout);
+      meminfo->pswpout = val;
     } else if (tokens[0] == "pgmajfault") {
-      StringToInt(tokens[1], &meminfo->pgmajfault);
+      meminfo->pgmajfault = val;
     }
   }
 

base/process/process_metrics_unittest.cc

@@ -286,13 +286,13 @@ TEST_F(SystemMetricsTest, ParseVmstat) {
     "pgrefill_high 0\n"
     "pgrefill_movable 0\n";
   EXPECT_TRUE(ParseProcVmstat(valid_input1, &meminfo));
-  EXPECT_EQ(meminfo.pswpin, 179);
-  EXPECT_EQ(meminfo.pswpout, 406);
-  EXPECT_EQ(meminfo.pgmajfault, 487192);
+  EXPECT_EQ(179LU, meminfo.pswpin);
+  EXPECT_EQ(406LU, meminfo.pswpout);
+  EXPECT_EQ(487192LU, meminfo.pgmajfault);
   EXPECT_TRUE(ParseProcVmstat(valid_input2, &meminfo));
-  EXPECT_EQ(meminfo.pswpin, 12);
-  EXPECT_EQ(meminfo.pswpout, 901);
-  EXPECT_EQ(meminfo.pgmajfault, 2023);
+  EXPECT_EQ(12LU, meminfo.pswpin);
+  EXPECT_EQ(901LU, meminfo.pswpout);
+  EXPECT_EQ(2023LU, meminfo.pgmajfault);
 }
 #endif  // defined(OS_LINUX) || defined(OS_ANDROID)