Comment tweaks.

Improve the readability. "an string" -> "a string", mostly.

Bug: None
Change-Id: I71ef9fa7545e23c977a7b90192161776d69cf527
Reviewed-on: https://chromium-review.googlesource.com/c/1180275Reviewed-by: Mike Pinkerton <pinkerton@chromium.org>
Reviewed-by: Will Harris <wfh@chromium.org>
Reviewed-by: Dan Erat <derat@chromium.org>
Commit-Queue: Peter Mayo <petermayo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616033}

ash/system/power/power_status.h

@@ -188,7 +188,7 @@ class ASH_EXPORT PowerStatus : public chromeos::PowerManagerClient::Observer {
                                         SkColor bg_color,
                                         SkColor fg_color);
 
-  // Returns an string describing the current state for accessibility.
+  // Returns a string describing the current state for accessibility.
   base::string16 GetAccessibleNameString(bool full_description) const;
 
   // Returns status strings that are generated by current PowerStatus.

chrome/test/data/extensions/input_ime/main.js

@@ -238,7 +238,7 @@ EngineBridge.prototype = {
   /**
    * Returns active engine ID. Returns null if there is no active engine.
    * @this EngineBridge
-   * @return {string} An string which identify the engine.
+   * @return {string} A string that identifies the engine.
    **/
   getActiveEngineID: function() {
     return this.activeEngine_;

components/policy/proto/device_management_backend.proto

@@ -905,7 +905,7 @@ message AppStatus {
 
 // Chrome user profile level status.
 message ChromeUserProfileReport {
-  // An string to uniquely identify this profile within the browser.
+  // A string to uniquely identify this profile within the browser.
   optional string id = 1;
   // A JSON encoded string containing both the “email” and “id” (obfuscated
   // GaiaID) of the user signed in to the Chrome browser, if any.

net/tools/cachetool/cachetool.cc

@@ -101,7 +101,7 @@ class CommandMarshal {
     return index;
   }
 
-  // Reads the next parameter as an string.
+  // Reads the next parameter as a string.
   virtual std::string ReadString() = 0;
 
   // Reads the next parameter from stdin as string.

sandbox/win/src/policy_engine_opcodes.h

@@ -170,7 +170,7 @@ class PolicyOpcode {
     *reinterpret_cast<T*>(&arguments_[index].mem) = argument;
   }
 
-  // Retrieves the actual address of an string argument. When using
+  // Retrieves the actual address of a string argument. When using
   // GetArgument() to retrieve an index that contains a string, the returned
   // value is just an offset to the actual string.
   // index: the stored string index. Valid values are from 0

third_party/blink/renderer/platform/wtf/text/string_view.h

@@ -57,7 +57,7 @@ class WTF_EXPORT StringView {
   StringView(StringImpl&, unsigned offset);
   StringView(StringImpl&, unsigned offset, unsigned length);
 
-  // From an String, implemented in String.h
+  // From a String, implemented in String.h
   inline StringView(const String&, unsigned offset, unsigned length);
   inline StringView(const String&, unsigned offset);
   inline StringView(const String&);